diff --git a/app/controllers/repp/v1/domains_controller.rb b/app/controllers/repp/v1/domains_controller.rb
index ed86638e4..e5887fb98 100644
--- a/app/controllers/repp/v1/domains_controller.rb
+++ b/app/controllers/repp/v1/domains_controller.rb
@@ -80,7 +80,7 @@ module Repp
         handle_errors(@domain) and return unless action.call
         # rubocop:enable Style/AndOr
 
-        render_success(data: { domain: { name: @domain.name,
+        render_success(message: message, data: { domain: { name: @domain.name,
                                          transfer_code: @domain.transfer_code,
                                          id: @domain.reload.uuid } })
       end
@@ -104,7 +104,7 @@ module Repp
           return
         end
 
-        render_success(data: { domain: { name: @domain.name } })
+        render_success(message: message, data: { domain: { name: @domain.name } })
       end
 
       api :GET, '/repp/v1/domains/:domain_name/transfer_info'
@@ -239,6 +239,10 @@ module Repp
         index_params[:offset] || 0
       end
 
+      def message
+        "Command completed successfully#{@domain.skipped_domain_contacts_validation if @domain.skipped_domain_contacts_validation.present?}"
+      end
+
       def index_params
         params.permit(:limit, :offset, :details, :simple, :q,
                       q: %i[s name_matches registrant_code_eq contacts_ident_eq
diff --git a/app/interactions/actions/domain_create.rb b/app/interactions/actions/domain_create.rb
index bd4f032d2..ef413a8db 100644
--- a/app/interactions/actions/domain_create.rb
+++ b/app/interactions/actions/domain_create.rb
@@ -15,7 +15,6 @@ module Actions
       assign_registrant
       assign_nameservers
       assign_domain_contacts
-      # domain.attach_default_contacts
       assign_expiry_time
       maybe_attach_legal_doc
 
@@ -38,7 +37,69 @@ module Actions
       false
     end
 
-    # Check if domain is eligible for new registration
+    def check_for_cross_role_duplicates
+      @removed_duplicates = []
+      
+      registrant_contact = domain.registrant
+      return true unless registrant_contact
+      
+      @admin_contacts = remove_duplicate_contacts(@admin_contacts, registrant_contact, 'admin')
+      @tech_contacts = remove_duplicate_contacts(@tech_contacts, registrant_contact, 'tech')
+      
+      @admin_contacts.each do |admin|
+        contact = Contact.find_by(id: admin[:contact_id])
+        next unless contact
+        
+        @tech_contacts = remove_duplicate_contacts(@tech_contacts, contact, 'tech')
+      end
+      
+      notify_about_removed_duplicates unless @removed_duplicates.empty?
+      
+      true
+    end
+    
+    def remove_duplicate_contacts(contacts_array, reference_contact, role)
+      return contacts_array unless reference_contact
+      
+      non_duplicates = contacts_array.reject do |contact_hash|
+        contact = Contact.find_by(id: contact_hash[:contact_id])
+        next false unless contact
+        
+        is_duplicate = duplicate_contact?(contact, reference_contact)
+        if is_duplicate
+          @removed_duplicates << { 
+            role: role, 
+            code: contact.code,
+            duplicate_of: reference_contact.code
+          }
+        end
+        is_duplicate
+      end
+      
+      non_duplicates
+    end
+    
+    def duplicate_contact?(contact1, contact2)
+      return false unless contact1 && contact2
+
+      contact1.code == contact2.code ||
+        (contact1.name == contact2.name &&
+         contact1.ident == contact2.ident &&
+         contact1.email == contact2.email &&
+         contact1.phone == contact2.phone)
+    end
+    
+    def notify_about_removed_duplicates
+      return if @removed_duplicates.empty?
+      
+      message = ''
+      @removed_duplicates.each do |duplicate|
+        message += ". #{duplicate[:role].capitalize} contact #{duplicate[:code]} was discarded as duplicate;"
+      end
+
+      domain.skipped_domain_contacts_validation = message
+    end
+
     def validate_domain_integrity
       return unless Domain.release_to_auction
 
@@ -132,9 +193,11 @@ module Actions
       params[:admin_contacts]&.each { |c| assign_contact(c) }
       params[:tech_contacts]&.each { |c| assign_contact(c, admin: false) }
 
+      check_contact_duplications
+      check_for_cross_role_duplicates
+      
       domain.admin_domain_contacts_attributes = @admin_contacts
       domain.tech_domain_contacts_attributes = @tech_contacts
-      check_contact_duplications
     end
 
     def assign_expiry_time
diff --git a/app/interactions/actions/domain_update.rb b/app/interactions/actions/domain_update.rb
index 36752b2a0..d035788d1 100644
--- a/app/interactions/actions/domain_update.rb
+++ b/app/interactions/actions/domain_update.rb
@@ -29,6 +29,7 @@ module Actions
 
       assign_admin_contact_changes
       assign_tech_contact_changes
+      check_for_cross_role_duplicates
     end
 
     def check_for_same_contacts(contacts, contact_type)
@@ -37,6 +38,150 @@ module Actions
       domain.add_epp_error('2306', contact_type, nil, %i[domain_contacts invalid])
     end
 
+    def check_for_cross_role_duplicates
+      @removed_duplicates = []
+      registrant_contact = domain.registrant
+      return true unless registrant_contact
+
+      current_admin_contacts = domain.admin_domain_contacts.map { |dc| { contact_id: dc.contact_id, contact_code: dc.contact.code } }
+      current_tech_contacts = domain.tech_domain_contacts.map { |dc| { contact_id: dc.contact_id, contact_code: dc.contact.code } }
+
+      updated_admin_contacts = remove_duplicate_contacts(current_admin_contacts, registrant_contact, 'admin')
+
+      updated_tech_contacts = remove_duplicate_contacts(current_tech_contacts, registrant_contact, 'tech')
+
+      if updated_admin_contacts.present?
+        updated_admin_contacts.each do |admin_hash|
+          admin_contact_object = Contact.find_by(id: admin_hash[:contact_id])
+          next unless admin_contact_object
+          updated_tech_contacts = remove_duplicate_contacts(updated_tech_contacts, admin_contact_object, 'tech')
+        end
+      end
+
+      admin_ids_after_filtering = updated_admin_contacts.map { |c| c[:contact_id] }
+      current_admin_ids_from_map = current_admin_contacts.map { |c| c[:contact_id] }
+      domain.admin_contact_ids = admin_ids_after_filtering if admin_ids_after_filtering.sort != current_admin_ids_from_map.sort
+
+      tech_ids_after_filtering = updated_tech_contacts.map { |c| c[:contact_id] }
+      current_tech_ids_from_map = current_tech_contacts.map { |c| c[:contact_id] }
+      domain.tech_contact_ids = tech_ids_after_filtering if tech_ids_after_filtering.sort != current_tech_ids_from_map.sort
+
+      notify_about_removed_duplicates unless @removed_duplicates.empty?
+
+      true
+    end
+
+    def remove_duplicate_contacts(contacts_array, reference_contact, role)
+      return contacts_array unless reference_contact && contacts_array.present?
+
+      contacts_array.reject do |contact_hash|
+        contact = Contact.find_by(id: contact_hash[:contact_id])
+        next false unless contact
+
+        is_duplicate = duplicate_contact?(contact, reference_contact)
+        if is_duplicate
+          @removed_duplicates << {
+            role: role,
+            code: contact.code,
+            duplicate_of: reference_contact.code
+          }
+        end
+        is_duplicate
+      end
+    end
+
+    def duplicate_contact?(contact1, contact2)
+      return false unless contact1 && contact2
+
+      contact1.code == contact2.code ||
+        (contact1.name == contact2.name &&
+         contact1.ident == contact2.ident &&
+         contact1.email == contact2.email &&
+         contact1.phone == contact2.phone)
+    end
+
+    def filter_duplicate_contacts_before_assignment(props, role)
+      @removed_duplicates ||= []
+      registrant = domain.registrant
+      
+      # Get existing contacts
+      existing_admin_contacts = domain.admin_domain_contacts.map(&:contact)
+      existing_tech_contacts = domain.tech_domain_contacts.map(&:contact)
+      
+      # Filter new contacts being added
+      filtered_props = props.select do |prop|
+        next true if prop[:_destroy] # Keep removal operations
+        
+        new_contact = Contact.find_by(id: prop[:contact_id])
+        next false unless new_contact
+        
+        # Check against registrant
+        if registrant && duplicate_contact?(new_contact, registrant)
+          @removed_duplicates << {
+            role: role,
+            code: new_contact.code,
+            duplicate_of: registrant.code
+          }
+          next false
+        end
+        
+        # Check against existing admin contacts
+        is_duplicate = existing_admin_contacts.any? { |existing| duplicate_contact?(new_contact, existing) }
+        if is_duplicate && role == 'admin'
+          duplicate_of = existing_admin_contacts.find { |existing| duplicate_contact?(new_contact, existing) }
+          @removed_duplicates << {
+            role: role,
+            code: new_contact.code,
+            duplicate_of: duplicate_of.code
+          }
+          next false
+        end
+        
+        # Check against existing tech contacts
+        is_duplicate = existing_tech_contacts.any? { |existing| duplicate_contact?(new_contact, existing) }
+        if is_duplicate && role == 'tech'
+          duplicate_of = existing_tech_contacts.find { |existing| duplicate_contact?(new_contact, existing) }
+          @removed_duplicates << {
+            role: role,
+            code: new_contact.code,
+            duplicate_of: duplicate_of.code
+          }
+          next false
+        end
+        
+        # For tech contacts, also check against admin contacts
+        if role == 'tech'
+          is_duplicate = existing_admin_contacts.any? { |existing| duplicate_contact?(new_contact, existing) }
+          if is_duplicate
+            duplicate_of = existing_admin_contacts.find { |existing| duplicate_contact?(new_contact, existing) }
+            @removed_duplicates << {
+              role: role,
+              code: new_contact.code,
+              duplicate_of: duplicate_of.code
+            }
+            next false
+          end
+        end
+        
+        true
+      end
+      
+      notify_about_removed_duplicates unless @removed_duplicates.empty?
+      filtered_props
+    end
+
+    def notify_about_removed_duplicates
+      return if @removed_duplicates.empty?
+
+      # Template: Admin contact EE123:DFD39958 was discarded as duplicate
+      message = ''
+      @removed_duplicates.each do |duplicate|
+        message += ". #{duplicate[:role].capitalize} contact #{duplicate[:code]} was discarded as duplicate;"
+      end
+
+      domain.skipped_domain_contacts_validation = message
+    end
+
     def validate_domain_integrity
       domain.auth_info = params[:transfer_code] if params[:transfer_code]
 
@@ -161,8 +306,10 @@ module Actions
         domain.add_epp_error('2304', 'admin', DomainStatus::SERVER_ADMIN_CHANGE_PROHIBITED,
                              I18n.t(:object_status_prohibits_operation))
       elsif props.present?
-        domain.admin_domain_contacts_attributes = props
-        check_for_same_contacts(props, 'admin')
+        # Filter duplicates before assignment
+        props = filter_duplicate_contacts_before_assignment(props, 'admin')
+        domain.admin_domain_contacts_attributes = props if props.present?
+        check_for_same_contacts(props, 'admin') if props.present?
       end
     end
 
@@ -176,8 +323,10 @@ module Actions
         domain.add_epp_error('2304', 'tech', DomainStatus::SERVER_TECH_CHANGE_PROHIBITED,
                              I18n.t(:object_status_prohibits_operation))
       elsif props.present?
-        domain.tech_domain_contacts_attributes = props
-        check_for_same_contacts(props, 'tech')
+        # Filter duplicates before assignment
+        props = filter_duplicate_contacts_before_assignment(props, 'tech')
+        domain.tech_domain_contacts_attributes = props if props.present?
+        check_for_same_contacts(props, 'tech') if props.present?
       end
     end
 
diff --git a/app/models/domain.rb b/app/models/domain.rb
index 809d18615..f539d0b73 100644
--- a/app/models/domain.rb
+++ b/app/models/domain.rb
@@ -93,6 +93,7 @@ class Domain < ApplicationRecord
   has_one :csync_record, dependent: :destroy
 
   attribute :skip_whois_record_update, :boolean, default: false
+  attribute :skipped_domain_contacts_validation, :string, default: ''
 
   after_initialize do
     self.pending_json = {} if pending_json.blank?
diff --git a/app/views/epp/domains/create.xml.builder b/app/views/epp/domains/create.xml.builder
index 70710e685..f793d8698 100644
--- a/app/views/epp/domains/create.xml.builder
+++ b/app/views/epp/domains/create.xml.builder
@@ -1,7 +1,7 @@
 xml.epp_head do
   xml.response do
     xml.result('code' => '1000') do
-      xml.msg 'Command completed successfully'
+      xml.msg "Command completed successfully#{@domain.skipped_domain_contacts_validation if @domain.skipped_domain_contacts_validation.present?}"
     end
 
     xml.resData do
diff --git a/app/views/epp/domains/success.xml.builder b/app/views/epp/domains/success.xml.builder
index a111f92d0..f391c7427 100644
--- a/app/views/epp/domains/success.xml.builder
+++ b/app/views/epp/domains/success.xml.builder
@@ -1,7 +1,7 @@
 xml.epp_head do
   xml.response do
     xml.result('code' => '1000') do
-      xml.msg 'Command completed successfully'
+      xml.msg "Command completed successfully#{@domain.skipped_domain_contacts_validation if @domain && @domain.respond_to?(:skipped_domain_contacts_validation) && @domain.skipped_domain_contacts_validation.present?}"
     end
 
     render('epp/shared/trID', builder: xml)
diff --git a/test/integration/epp/domain/create/base_test.rb b/test/integration/epp/domain/create/base_test.rb
index 73b6f3abe..3f1d31f93 100644
--- a/test/integration/epp/domain/create/base_test.rb
+++ b/test/integration/epp/domain/create/base_test.rb
@@ -603,7 +603,8 @@ class EppDomainCreateBaseTest < EppTestCase
     travel_to now
     name = "new.#{dns_zones(:one).origin}"
     contact = contacts(:john)
-    registrant = contact.becomes(Registrant)
+    # registrant = contact.becomes(Registrant)
+    registrant = contacts(:william)
 
     registrant.update!(ident_type: 'org')
     registrant.reload
@@ -639,7 +640,7 @@ class EppDomainCreateBaseTest < EppTestCase
 
     domain = Domain.find_by(name: name)
     assert_equal name, domain.name
-    assert_equal registrant, domain.registrant
+    assert_equal registrant.code, domain.registrant.code
     assert_equal [contact], domain.admin_contacts
     assert_empty domain.tech_contacts
     assert_not_empty domain.transfer_code
@@ -1186,4 +1187,434 @@ class EppDomainCreateBaseTest < EppTestCase
     assert_correct_against_schema response_xml
     assert_epp_response :completed_successfully
   end
+
+  def test_registers_domain_with_duplicate_registrant_and_admin
+    duplicate_contact = Contact.create!(
+      name: 'Duplicate Test',
+      code: 'duplicate-001',
+      email: 'duplicate@test.com',
+      phone: '+123.4567890',
+      ident: '12345X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    admin_contact = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-001',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: duplicate_contact.ident_type,
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    name = "domain-reg-admin-duplicate-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin_contact.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+    
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert response.body.include? "Admin contact #{admin_contact.code} was discarded as duplicate;"
+  end
+  
+  def test_domain_with_duplicate_registrant_one_of_multiple_admins
+    duplicate_contact = Contact.create!(
+      name: 'Duplicate Test',
+      code: 'duplicate-002',
+      email: 'duplicate@test.com',
+      phone: '+123.4567890',
+      ident: '12345X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    admin1 = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-002',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: duplicate_contact.ident_type,
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    admin2 = contacts(:william)
+    name = "domain-reg-admin-multiple-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin1.code}</domain:contact>
+              <domain:contact type="admin">#{admin2.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert_equal 1, domain.admin_contacts.count, "Should have only one admin contact"
+    assert_equal admin2.code, domain.admin_contacts.first.code, "Should keep the non-duplicate admin"
+    
+    assert response.body.include? "Admin contact #{admin1.code} was discarded as duplicate;"
+  end
+  
+  def test_domain_with_duplicate_admin_and_tech
+    registrant = contacts(:acme_ltd).becomes(Registrant)
+    
+    admin = Contact.create!(
+      name: 'Duplicate Admin Tech Test',
+      code: 'duplicate-admin-003',
+      email: 'admin-tech@test.com',
+      phone: '+123.4567890',
+      ident: '12346X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    tech = Contact.create!(
+      name: admin.name,
+      code: 'duplicate-tech-003',
+      email: admin.email,
+      phone: admin.phone,
+      ident: admin.ident,
+      ident_type: admin.ident_type,
+      ident_country_code: admin.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    name = "domain-admin-tech-duplicate-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin.code}</domain:contact>
+              <domain:contact type="tech">#{tech.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+    
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert_equal 1, domain.admin_contacts.count, "Should have one admin contact"
+    assert_equal admin.code, domain.admin_contacts.first.code, "Should keep the admin contact"
+    assert_empty domain.tech_contacts, "Tech contacts should be empty due to duplication with admin"
+    
+    assert response.body.include? "Tech contact #{tech.code} was discarded as duplicate;"
+  end
+  
+  def test_domain_with_duplicate_one_admin_one_tech
+    registrant = contacts(:acme_ltd).becomes(Registrant)
+    
+    admin1 = Contact.create!(
+      name: 'First Admin',
+      code: 'duplicate-admin-004',
+      email: 'first-admin@test.com',
+      phone: '+123.4567890',
+      ident: '12347X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    admin2 = contacts(:william)
+
+    tech1 = Contact.create!(
+      name: admin1.name,
+      code: 'duplicate-tech-004',
+      email: admin1.email,
+      phone: admin1.phone,
+      ident: admin1.ident,
+      ident_type: admin1.ident_type,
+      ident_country_code: admin1.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    tech2 = contacts(:jack)
+    
+    name = "domain-one-admin-one-tech-dup-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin1.code}</domain:contact>
+              <domain:contact type="admin">#{admin2.code}</domain:contact>
+              <domain:contact type="tech">#{tech1.code}</domain:contact>
+              <domain:contact type="tech">#{tech2.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+    
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert_equal 2, domain.admin_contacts.count, "Should have both admin contacts"
+    
+    tech_contacts = domain.tech_contacts
+    assert_equal 1, tech_contacts.count, "Should have only the non-duplicate tech contact"
+    assert_equal tech2.code, tech_contacts.first.code, "Should keep the non-duplicate tech contact"
+    
+    assert response.body.include? "Tech contact #{tech1.code} was discarded as duplicate;"
+  end
+  
+  def test_domain_with_duplicate_registrant_admin_tech
+    duplicate_contact = Contact.create!(
+      name: 'Full Duplicate Test',
+      code: 'duplicate-005',
+      email: 'full-duplicate@test.com',
+      phone: '+123.5678901',
+      ident: '12348X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    admin = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-005',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: duplicate_contact.ident_type,
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    tech = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-tech-005',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: duplicate_contact.ident_type,
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    name = "domain-all-duplicates-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin.code}</domain:contact>
+              <domain:contact type="tech">#{tech.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert_empty domain.admin_contacts, "Admin contacts should be empty due to duplication"
+    assert_empty domain.tech_contacts, "Tech contacts should be empty due to duplication"
+    assert response.body.include? "Admin contact #{admin.code} was discarded as duplicate;"
+    assert response.body.include? "Tech contact #{tech.code} was discarded as duplicate;"
+  end
+  
+  def test_domain_with_duplicate_registrant_one_admin_one_tech
+    duplicate_contact = Contact.create!(
+      name: 'Partial Duplicate Test',
+      code: 'duplicate-006',
+      email: 'partial-duplicate@test.com',
+      phone: '+123.6789012',
+      ident: '12349X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    admin1 = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-006',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: 'priv',
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    admin2 = contacts(:jack)
+    admin2.ident_type = 'priv'
+    admin2.save!
+    
+    tech1 = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-tech-006',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: duplicate_contact.ident_type,
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+    
+    tech2 = contacts(:william)
+    
+    name = "domain-partial-duplicates-#{Time.now.to_i}.#{dns_zones(:one).origin}"
+    
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <create>
+            <domain:create xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{name}</domain:name>
+              <domain:registrant>#{registrant.code}</domain:registrant>
+              <domain:contact type="admin">#{admin1.code}</domain:contact>
+              <domain:contact type="admin">#{admin2.code}</domain:contact>
+              <domain:contact type="tech">#{tech1.code}</domain:contact>
+              <domain:contact type="tech">#{tech2.code}</domain:contact>
+            </domain:create>
+          </create>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    assert_difference 'Domain.count', 1 do
+      post epp_create_path, params: { frame: request_xml },
+           headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    end
+    
+    response_xml = Nokogiri::XML(response.body)
+    assert_correct_against_schema response_xml
+    assert_epp_response :completed_successfully
+    
+    domain = Domain.find_by(name: name)
+    assert_not_nil domain, "Domain should have been created"
+    assert_equal 1, domain.admin_contacts.count, "Should have only the non-duplicate admin contact"
+    assert_equal admin2.code, domain.admin_contacts.first.code, "Should keep the non-duplicate admin contact"
+    assert_equal 1, domain.tech_contacts.count, "Should have only the non-duplicate tech contact"
+    assert_equal tech2.code, domain.tech_contacts.first.code, "Should keep the non-duplicate tech contact"
+    
+    assert response.body.include? "Admin contact #{admin1.code} was discarded as duplicate;"
+    assert response.body.include? "Tech contact #{tech1.code} was discarded as duplicate;"
+  end
 end
diff --git a/test/integration/epp/domain/update/base_test.rb b/test/integration/epp/domain/update/base_test.rb
index a8c2045c9..70b1fd355 100644
--- a/test/integration/epp/domain/update/base_test.rb
+++ b/test/integration/epp/domain/update/base_test.rb
@@ -1091,6 +1091,229 @@ class EppDomainUpdateBaseTest < EppTestCase
     assert_epp_response :object_status_prohibits_operation
   end
 
+  # UPDATE TESTS FOR DUPLICATE CONTACTS
+  def test_update_domain_with_duplicate_registrant_and_single_admin
+    domain = domains(:shop)
+    
+    duplicate_contact = Contact.create!(
+      name: 'Partial Duplicate Test',
+      code: 'duplicate-006',
+      email: 'partial-duplicate@test.com',
+      phone: '+123.6789012',
+      ident: '12349X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    new_admin = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-006',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: 'priv',
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+
+    domain.update(registrant: registrant) && domain.reload
+
+    old_admin = domain.admin_contacts.first
+
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <update>
+            <domain:update xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{domain.name}</domain:name>
+              <domain:chg/>
+              <domain:add>
+                <domain:contact type="admin">#{new_admin.code}</domain:contact>
+              </domain:add>
+              <domain:rem>
+                <domain:contact type="admin">#{old_admin.code}</domain:contact>
+              </domain:rem>
+            </domain:update>
+          </update>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    post epp_update_path(domain_name: domain.name), params: { frame: request_xml }, headers: { 'HTTP_COOKIE' => 'session=api_bestnames' }
+    domain.reload
+
+    assert_epp_response :completed_successfully
+    assert response.body.include? "Admin contact #{new_admin.code} was discarded as duplicate;"
+  end
+
+  def test_update_domain_with_registrant_admin_tech_all_duplicates
+    domain = domains(:airport)
+
+    initial_admin_contact = contacts(:jane)
+    initial_tech_contact = contacts(:william)
+    domain.admin_contacts = [initial_admin_contact]
+    domain.tech_contacts = [initial_tech_contact]
+    domain.save!
+    domain.reload
+
+    base_duplicate_data_contact = Contact.create!(
+      name: 'All Roles Are The Same Person',
+      code: "base-all-roles-#{SecureRandom.hex(3)}",
+      email: 'all.roles.same.person@example.com',
+      phone: '+1.999888777',
+      ident: 'ARSAMEP123',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: domain.registrar
+    )
+
+    new_registrant = base_duplicate_data_contact.becomes(Registrant)
+    domain.update!(registrant: new_registrant)
+    domain.reload
+
+    new_admin_being_added = Contact.create!(
+      name: base_duplicate_data_contact.name,
+      code: "admin-dup-all-roles-#{SecureRandom.hex(3)}",
+      email: base_duplicate_data_contact.email,
+      phone: base_duplicate_data_contact.phone,
+      ident: base_duplicate_data_contact.ident,
+      ident_type: base_duplicate_data_contact.ident_type,
+      ident_country_code: base_duplicate_data_contact.ident_country_code,
+      registrar: domain.registrar
+    )
+
+    new_tech_being_added = Contact.create!(
+      name: base_duplicate_data_contact.name,
+      code: "tech-dup-all-roles-#{SecureRandom.hex(3)}",
+      email: base_duplicate_data_contact.email,
+      phone: base_duplicate_data_contact.phone,
+      ident: base_duplicate_data_contact.ident,
+      ident_type: base_duplicate_data_contact.ident_type,
+      ident_country_code: base_duplicate_data_contact.ident_country_code,
+      registrar: domain.registrar
+    )
+
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <update>
+            <domain:update xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{domain.name}</domain:name>
+              <domain:chg/>
+              <domain:add>
+                <domain:contact type="admin">#{new_admin_being_added.code}</domain:contact>
+                <domain:contact type="tech">#{new_tech_being_added.code}</domain:contact>
+              </domain:add>
+              <domain:rem>
+                <domain:contact type="admin">#{initial_admin_contact.code}</domain:contact>
+                <domain:contact type="tech">#{initial_tech_contact.code}</domain:contact>
+              </domain:rem>
+            </domain:update>
+          </update>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    post epp_update_path(domain_name: domain.name), params: { frame: request_xml }, headers: { 'HTTP_COOKIE' => "session=api_bestnames" }
+    domain.reload
+
+    assert_epp_response :completed_successfully
+    assert response.body.include? "Admin contact #{new_admin_being_added.code} was discarded as duplicate;"
+    assert response.body.include? "Tech contact #{new_tech_being_added.code} was discarded as duplicate;"
+  end
+
+  def test_update_domain_with_duplicate_admin_and_tech_registrant_is_different
+    domain = domains(:library)
+
+    initial_admin_contact = contacts(:john)
+    initial_tech_contact = contacts(:william)
+    domain.admin_contacts = [initial_admin_contact]
+    domain.tech_contacts = [initial_tech_contact]
+    domain.save!
+    domain.reload
+
+    admin_tech_duplicate_base = Contact.create!(
+      name: 'Admin And Tech Are Same Person',
+      code: "base-adm-tech-#{SecureRandom.hex(3)}",
+      email: 'admin.tech.same.person@example.com',
+      phone: '+1.555444333',
+      ident: 'ATSAMEP456',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: domain.registrar
+    )
+
+    new_admin_being_added = Contact.create!(
+      name: admin_tech_duplicate_base.name,
+      code: "admin-dup-adm-tech-#{SecureRandom.hex(3)}",
+      email: admin_tech_duplicate_base.email,
+      phone: admin_tech_duplicate_base.phone,
+      ident: admin_tech_duplicate_base.ident,
+      ident_type: admin_tech_duplicate_base.ident_type,
+      ident_country_code: admin_tech_duplicate_base.ident_country_code,
+      registrar: domain.registrar
+    )
+
+    new_tech_being_added_and_skipped = Contact.create!(
+      name: admin_tech_duplicate_base.name,
+      code: "tech-dup-adm-tech-#{SecureRandom.hex(3)}",
+      email: admin_tech_duplicate_base.email,
+      phone: admin_tech_duplicate_base.phone,
+      ident: admin_tech_duplicate_base.ident,
+      ident_type: admin_tech_duplicate_base.ident_type,
+      ident_country_code: admin_tech_duplicate_base.ident_country_code,
+      registrar: domain.registrar
+    )
+
+    request_xml = <<-XML
+      <?xml version="1.0" encoding="UTF-8" standalone="no"?>
+      <epp xmlns="#{Xsd::Schema.filename(for_prefix: 'epp-ee', for_version: '1.0')}">
+        <command>
+          <update>
+            <domain:update xmlns:domain="#{Xsd::Schema.filename(for_prefix: 'domain-ee', for_version: '1.2')}">
+              <domain:name>#{domain.name}</domain:name>
+              <domain:chg/>
+              <domain:add>
+                <domain:contact type="admin">#{new_admin_being_added.code}</domain:contact>
+                <domain:contact type="tech">#{new_tech_being_added_and_skipped.code}</domain:contact>
+              </domain:add>
+              <domain:rem>
+                <domain:contact type="admin">#{initial_admin_contact.code}</domain:contact>
+                <domain:contact type="tech">#{initial_tech_contact.code}</domain:contact>
+              </domain:rem>
+            </domain:update>
+          </update>
+          <extension>
+            <eis:extdata xmlns:eis="#{Xsd::Schema.filename(for_prefix: 'eis', for_version: '1.0')}">
+              <eis:legalDocument type="pdf">#{'test' * 2000}</eis:legalDocument>
+            </eis:extdata>
+          </extension>
+        </command>
+      </epp>
+    XML
+
+    post epp_update_path(domain_name: domain.name), params: { frame: request_xml }, headers: { 'HTTP_COOKIE' => "session=api_bestnames" }
+    domain.reload
+
+    assert_epp_response :completed_successfully
+    assert response.body.include? "Tech contact #{new_tech_being_added_and_skipped.code} was discarded as duplicate;"
+  end
+
   private
 
   def assert_verification_and_notification_emails
diff --git a/test/integration/repp/v1/domains/contacts_test.rb b/test/integration/repp/v1/domains/contacts_test.rb
index df472bad4..28025f2f0 100644
--- a/test/integration/repp/v1/domains/contacts_test.rb
+++ b/test/integration/repp/v1/domains/contacts_test.rb
@@ -51,7 +51,10 @@ class ReppV1DomainsContactsTest < ActionDispatch::IntegrationTest
     assert_response :ok
     assert_equal 1000, json[:code]
 
-    assert @domain.admin_contacts.find_by(code: new_contact.code).present?
+    # Becase we implemented feature which allows us avoid duplicates of contacts, 
+    # I changed this value from assert to assert_not. 
+    # PS! Tech contact and registrant are same, that's why tech contact is not added.
+    assert_not @domain.admin_contacts.find_by(code: new_contact.code).present?
   end
 
   def test_can_add_new_tech_contacts
@@ -66,13 +69,16 @@ class ReppV1DomainsContactsTest < ActionDispatch::IntegrationTest
     assert_equal 1000, json[:code]
     @domain.reload
 
-    assert @domain.tech_contacts.find_by(code: new_contact.code).present?
+    # Becase we implemented feature which allows us avoid duplicates of contacts, 
+    # I changed this value from assert to assert_not. 
+    # PS! Tech contact and registrant are same, that's why tech contact is not added.
+    assert_not @domain.tech_contacts.find_by(code: new_contact.code).present?
   end
 
   def test_can_remove_admin_contacts
     Spy.on_instance_method(Actions::DomainUpdate, :validate_email).and_return(true)
 
-    contact = contacts(:john)
+    contact = contacts(:william)
     payload = { contacts: [ { code: contact.code, type: 'admin' } ] }
     post "/repp/v1/domains/#{@domain.name}/contacts", headers: @auth_headers, params: payload
     assert @domain.admin_contacts.find_by(code: contact.code).present?
@@ -90,7 +96,7 @@ class ReppV1DomainsContactsTest < ActionDispatch::IntegrationTest
   def test_can_remove_tech_contacts
     Spy.on_instance_method(Actions::DomainUpdate, :validate_email).and_return(true)
 
-    contact = contacts(:john)
+    contact = contacts(:william)
     payload = { contacts: [ { code: contact.code, type: 'tech' } ] }
     post "/repp/v1/domains/#{@domain.name}/contacts", headers: @auth_headers, params: payload
     assert @domain.tech_contacts.find_by(code: contact.code).present?
@@ -240,4 +246,47 @@ class ReppV1DomainsContactsTest < ActionDispatch::IntegrationTest
     assert_equal 1000, json[:code]
     assert_empty @domain.admin_contacts
   end
+
+  def test_updates_add_duplicate_admin_contact
+    domain = domains(:shop)
+    
+    duplicate_contact = Contact.create!(
+      name: 'Partial Duplicate Test',
+      code: 'duplicate-006',
+      email: 'partial-duplicate@test.com',
+      phone: '+123.6789012',
+      ident: '12349X',
+      ident_type: 'priv',
+      ident_country_code: 'US',
+      registrar: registrars(:bestnames)
+    )
+    
+    registrant = duplicate_contact.becomes(Registrant)
+    
+    new_admin = Contact.create!(
+      name: duplicate_contact.name,
+      code: 'duplicate-admin-006',
+      email: duplicate_contact.email,
+      phone: duplicate_contact.phone,
+      ident: duplicate_contact.ident,
+      ident_type: 'priv',
+      ident_country_code: duplicate_contact.ident_country_code,
+      registrar: registrars(:bestnames)
+    )
+
+    domain.update(registrant: registrant) && domain.reload
+
+    old_admin = domain.admin_contacts.first
+    assert_includes domain.admin_contacts, old_admin
+
+    payload = { contacts: [ { code: new_admin.code, type: 'admin' } ] }
+    post "/repp/v1/domains/#{domain.name}/contacts", headers: @auth_headers, params: payload
+    json = JSON.parse(response.body, symbolize_names: true)
+
+    assert_response :ok
+    assert_equal 1000, json[:code]
+
+    domain.reload
+    assert_not domain.admin_contacts.find_by(code: new_admin.code).present?
+  end
 end