diff --git a/app/controllers/affinities_controller.rb b/app/controllers/affinities_controller.rb
index 7d63e9e..1412423 100644
--- a/app/controllers/affinities_controller.rb
+++ b/app/controllers/affinities_controller.rb
@@ -26,7 +26,7 @@ class AffinitiesController < ApplicationController
       }
     end
 
-    GroupAffinity.upsert_all(affinities)
+    GroupAffinity.upsert_all(affinities, unique_by: :uindex_group_pair)
 
     render json: {}, status: :ok
   rescue ActiveRecord::InvalidForeignKey
@@ -50,7 +50,7 @@ class AffinitiesController < ApplicationController
       }
     end
 
-    GroupAffinity.upsert_all(affinities)
+    GroupAffinity.upsert_all(affinities, unique_by: :uindex_group_pair)
 
     render json: {}, status: :ok
   end