diff --git a/app/models/location.rb b/app/models/location.rb
index 728caf49d..03af24a94 100644
--- a/app/models/location.rb
+++ b/app/models/location.rb
@@ -133,10 +133,9 @@ class Location < ApplicationRecord
     scope.pluck("ARRAY_AGG(id)")
   }
 
-  scope :duplicate_sets_within_duplicate_schemes, lambda {
+  scope :duplicate_sets_within_given_schemes, lambda {
     scope = visible
     .group(*DUPLICATE_LOCATION_ATTRIBUTES - %w[scheme_id])
-    .where(scheme_id: nil)
     .where.not(postcode: nil)
     .where.not(mobility_type: nil)
     .having(
@@ -145,7 +144,7 @@ class Location < ApplicationRecord
     scope.pluck("ARRAY_AGG(id)")
   }
 
-  DUPLICATE_LOCATION_ATTRIBUTES = %w[postcode mobility_type].freeze
+  DUPLICATE_LOCATION_ATTRIBUTES = %w[scheme_id postcode mobility_type].freeze
   LOCAL_AUTHORITIES = LocalAuthority.all.map { |la| [la.name, la.code] }.to_h
 
   enum local_authorities: LOCAL_AUTHORITIES
diff --git a/lib/tasks/count_duplicates.rake b/lib/tasks/count_duplicates.rake
index ef4f53ec2..e65688b4d 100644
--- a/lib/tasks/count_duplicates.rake
+++ b/lib/tasks/count_duplicates.rake
@@ -35,7 +35,7 @@ namespace :count_duplicates do
         duplicate_sets_within_duplicate_schemes = []
         if organisation.owned_schemes.duplicate_sets.count.positive?
           organisation.owned_schemes.duplicate_sets.each do |duplicate_set|
-            duplicate_sets_within_duplicate_schemes += Location.where(scheme_id: duplicate_set).duplicate_sets
+            duplicate_sets_within_duplicate_schemes += Location.where(scheme_id: duplicate_set).duplicate_sets_within_given_schemes
           end
           duplicate_locations_within_duplicate_schemes_ids = duplicate_sets_within_duplicate_schemes.flatten