diff --git a/.rubocop_styleguide.yml b/.rubocop_styleguide.yml
index 42857db556..15f52ac883 100644
--- a/.rubocop_styleguide.yml
+++ b/.rubocop_styleguide.yml
@@ -44,6 +44,11 @@ Metrics/BlockLength:
     "xdescribe",
   ]
 
+Rails/ApplicationRecord:
+  Exclude:
+    # Migrations should not contain application code:
+    - "db/migrate/*.rb"
+
 Rails/SkipsModelValidations:
   AllowedMethods:
     - "touch"
diff --git a/app/models/customer.rb b/app/models/customer.rb
index de37b5094a..678c4a2d12 100644
--- a/app/models/customer.rb
+++ b/app/models/customer.rb
@@ -1,5 +1,12 @@
 # frozen_string_literal: true
 
+# A customer record is created the first time a person orders from a shop.
+#
+# It's a relationship between a user and an enterprise but for guest orders it
+# can also be between an email address and an enterprise.
+#
+# The main purpose is tagging of customers to access private shops, receive
+# discounts et cetera. A customer record is also needed for subscriptions.
 class Customer < ApplicationRecord
   include SetUnusedAddressFields
 
@@ -7,7 +14,7 @@ class Customer < ApplicationRecord
 
   searchable_attributes :first_name, :last_name, :email, :code
 
-  belongs_to :enterprise
+  belongs_to :enterprise, optional: false
   belongs_to :user, class_name: "Spree::User"
   has_many :orders, class_name: "Spree::Order"
   before_destroy :update_orders_and_delete_canceled_subscriptions
@@ -26,7 +33,6 @@ class Customer < ApplicationRecord
   validates :code, uniqueness: { scope: :enterprise_id, allow_nil: true }
   validates :email, presence: true, 'valid_email_2/email': true,
                     uniqueness: { scope: :enterprise_id, message: I18n.t('validation_msg_is_associated_with_an_exising_customer') }
-  validates :enterprise, presence: true
 
   scope :of, ->(enterprise) { where(enterprise_id: enterprise) }
 
diff --git a/db/migrate/20220907055044_delete_duplicate_customers.rb b/db/migrate/20220907055044_delete_duplicate_customers.rb
new file mode 100644
index 0000000000..f28faf0874
--- /dev/null
+++ b/db/migrate/20220907055044_delete_duplicate_customers.rb
@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+class DeleteDuplicateCustomers < ActiveRecord::Migration[6.1]
+  class Customer < ActiveRecord::Base
+    belongs_to :bill_address, class_name: "SpreeAddress"
+    belongs_to :ship_address, class_name: "SpreeAddress"
+
+    after_destroy do
+      destroy_unused_address(bill_address)
+      destroy_unused_address(ship_address)
+    end
+
+    def destroy_unused_address(record)
+      return unless record
+      return if in_use?(SpreeOrder, record)
+      return if in_use?(Customer, record)
+      return if in_use?(SpreeUser, record)
+
+      record.destroy
+    end
+
+    def in_use?(model, record)
+      model.where(bill_address_id: record).or(
+        model.where(ship_address_id: record)
+      ).present?
+    end
+  end
+
+  class SpreeAddress < ActiveRecord::Base
+  end
+
+  class SpreeOrder < ActiveRecord::Base
+  end
+
+  class Subscription < ActiveRecord::Base
+  end
+
+  class Customer < ActiveRecord::Base
+  end
+
+  class SpreeUser < ActiveRecord::Base
+  end
+
+  def up
+    say "#{grouped_duplicates.keys.count} customers with duplicates."
+
+    grouped_duplicates.map do |key, customers|
+      chosen = customers.first
+      others = customers - [chosen]
+
+      say "- #{key}"
+
+      # We can't tell which attributes or associations are the correct ones.
+      # Selection has been random so far and it's no regression to randomly
+      # select the attributes of the first customer record.
+      #
+      # However, we do need to update references to the customer.
+      update_references(others, chosen)
+
+      others.each(&:destroy!)
+    end
+  end
+
+  def grouped_duplicates
+    @grouped_duplicates ||= duplicate_records.group_by do |customer|
+      [customer.email, customer.enterprise_id]
+    end
+  end
+
+  def duplicate_records
+    customer_duplicates = <<~SQL
+      JOIN customers AS copy
+        ON customers.id != copy.id
+       AND customers.email = copy.email
+       AND customers.enterprise_id = copy.enterprise_id
+    SQL
+
+    Customer.joins(customer_duplicates)
+  end
+
+  def update_references(source_customers, destination_customer)
+    SpreeOrder.where(customer_id: source_customers.map(&:id)).
+      update_all(customer_id: destination_customer.id)
+
+    Subscription.where(customer_id: source_customers.map(&:id)).
+      update_all(customer_id: destination_customer.id)
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 6e3b0a3c87..6c9b1b00fe 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_07_13_195433) do
+ActiveRecord::Schema.define(version: 2022_09_07_055044) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_stat_statements"