diff --git a/app/models/duplicate_log_reference.rb b/app/models/duplicate_log_reference.rb
new file mode 100644
index 000000000..a8ef83444
--- /dev/null
+++ b/app/models/duplicate_log_reference.rb
@@ -0,0 +1,18 @@
+class DuplicateLogReference < ApplicationRecord
+  belongs_to :log, polymorphic: true
+
+  before_create :set_default_duplicate_log_reference_id
+
+private
+
+  def set_default_duplicate_log_reference_id
+    self.duplicate_log_reference_id ||= generate_new_id
+  end
+
+  def generate_new_id
+    loop do
+      duplicate_log_reference_id = SecureRandom.random_number(1_000_000)
+      return duplicate_log_reference_id unless DuplicateLogReference.exists?(duplicate_log_reference_id:)
+    end
+  end
+end
diff --git a/app/models/lettings_log.rb b/app/models/lettings_log.rb
index 3eda732d1..854acd79d 100644
--- a/app/models/lettings_log.rb
+++ b/app/models/lettings_log.rb
@@ -631,6 +631,10 @@ class LettingsLog < Log
     renttype == 1 || renttype == 2
   end
 
+  def duplicates
+    LettingsLog.joins(:duplicate_log_references).where(duplicate_log_references: { duplicate_log_reference_id: duplicate_log_references&.first&.duplicate_log_reference_id }).where.not(id:)
+  end
+
 private
 
   def reset_invalid_unresolved_log_fields!
diff --git a/app/models/log.rb b/app/models/log.rb
index 8814e771d..91964c43e 100644
--- a/app/models/log.rb
+++ b/app/models/log.rb
@@ -7,6 +7,7 @@ class Log < ApplicationRecord
   belongs_to :created_by, class_name: "User", optional: true
   belongs_to :updated_by, class_name: "User", optional: true
   belongs_to :bulk_upload, optional: true
+  has_many :duplicate_log_references, as: :log
 
   before_save :update_status!
 
diff --git a/app/models/sales_log.rb b/app/models/sales_log.rb
index cff497ae4..422e328d0 100644
--- a/app/models/sales_log.rb
+++ b/app/models/sales_log.rb
@@ -448,4 +448,8 @@ class SalesLog < Log
      form.start_date.year < 2023 || uprn.blank? ? "postcode_full" : nil,
      form.start_date.year >= 2023 && uprn.present? ? "uprn" : nil].compact
   end
+
+  def duplicates
+    SalesLog.joins(:duplicate_log_references).where(duplicate_log_references: { duplicate_log_reference_id: duplicate_log_references&.first&.duplicate_log_reference_id }).where.not(id:)
+  end
 end
diff --git a/db/migrate/20240110101500_create_duplicate_log_references.rb b/db/migrate/20240110101500_create_duplicate_log_references.rb
new file mode 100644
index 000000000..1edae4a38
--- /dev/null
+++ b/db/migrate/20240110101500_create_duplicate_log_references.rb
@@ -0,0 +1,11 @@
+class CreateDuplicateLogReferences < ActiveRecord::Migration[7.0]
+  def change
+    create_table :duplicate_log_references do |t|
+      t.integer :duplicate_log_reference_id
+      t.integer :log_id
+      t.string :log_type
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 22d67bb9f..58ebd5d95 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[7.0].define(version: 2023_12_18_105226) do
+ActiveRecord::Schema[7.0].define(version: 2024_01_10_101500) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -63,6 +63,14 @@ ActiveRecord::Schema[7.0].define(version: 2023_12_18_105226) do
     t.index ["organisation_id"], name: "index_data_protection_confirmations_on_organisation_id"
   end
 
+  create_table "duplicate_log_references", force: :cascade do |t|
+    t.integer "duplicate_log_reference_id"
+    t.integer "log_id"
+    t.string "log_type"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
   create_table "la_rent_ranges", force: :cascade do |t|
     t.integer "ranges_rent_id"
     t.integer "lettype"
diff --git a/spec/models/duplicate_log_reference_spec.rb b/spec/models/duplicate_log_reference_spec.rb
new file mode 100644
index 000000000..a92ce7d26
--- /dev/null
+++ b/spec/models/duplicate_log_reference_spec.rb
@@ -0,0 +1,89 @@
+require "rails_helper"
+
+RSpec.describe DuplicateLogReference, type: :model do
+  context "when adding a new duplicate log" do
+    context "and duplicate_log_reference_id is not given" do
+      let(:sales_log) { create(:sales_log) }
+
+      it "generates a new random duplicate_log_reference_id" do
+        duplicate_log = described_class.create!(log_id: sales_log.id, log_type: "SalesLog")
+        expect(duplicate_log.duplicate_log_reference_id).to be_a(Integer)
+      end
+    end
+
+    context "and duplicate_log_reference_id is given" do
+      let(:sales_log) { create(:sales_log) }
+
+      it "adds correct duplicate_log_reference_id" do
+        duplicate_log = described_class.create!(log_id: sales_log.id, log_type: "SalesLog", duplicate_log_reference_id: 123_456)
+        expect(duplicate_log.duplicate_log_reference_id).to eq(123_456)
+      end
+    end
+
+    context "and log does not exist" do
+      it "raises an error" do
+        expect { described_class.create!(log_id: 1, log_type: "SalesLog") }.to raise_error(ActiveRecord::RecordInvalid)
+      end
+    end
+
+    context "and log_type is invalid" do
+      let(:sales_log) { create(:sales_log) }
+
+      it "raises an error" do
+        expect { described_class.create!(log_id: sales_log.id, log_type: "SomethingElse") }.to raise_error(NameError)
+      end
+    end
+  end
+
+  context "when accessing all duplicates for a sales log" do
+    let(:sales_log) { create(:sales_log) }
+
+    context "and there are no duplicates" do
+      it "returns an empty array" do
+        expect(sales_log.duplicates).to eq([])
+      end
+    end
+
+    context "and there are duplicates" do
+      let(:other_sales_log) { create(:sales_log) }
+
+      before do
+        duplicate_log = described_class.create!(log_id: sales_log.id, log_type: "SalesLog")
+        described_class.create!(log_id: other_sales_log.id, log_type: "SalesLog", duplicate_log_reference_id: duplicate_log.duplicate_log_reference_id)
+        create(:sales_log)
+        create(:sales_log)
+      end
+
+      it "returns the correct duplicates" do
+        expect(sales_log.duplicates.count).to eq(1)
+        expect(sales_log.duplicates).to include(other_sales_log)
+      end
+    end
+  end
+
+  context "when accessing all duplicates for a lettings log" do
+    let(:lettings_log) { create(:lettings_log) }
+
+    context "and there are no duplicates" do
+      it "returns an empty array" do
+        expect(lettings_log.duplicates).to eq([])
+      end
+    end
+
+    context "and there are duplicates" do
+      let(:other_lettings_log) { create(:lettings_log) }
+
+      before do
+        duplicate_log = described_class.create!(log_id: lettings_log.id, log_type: "LettingsLog")
+        described_class.create!(log_id: other_lettings_log.id, log_type: "LettingsLog", duplicate_log_reference_id: duplicate_log.duplicate_log_reference_id)
+        create(:lettings_log)
+        create(:lettings_log)
+      end
+
+      it "returns the correct duplicates" do
+        expect(lettings_log.duplicates.count).to eq(1)
+        expect(lettings_log.duplicates).to include(other_lettings_log)
+      end
+    end
+  end
+end