diff --git a/app/graphql/types/doi_item.rb b/app/graphql/types/doi_item.rb
index d18964668..59a58537a 100644
--- a/app/graphql/types/doi_item.rb
+++ b/app/graphql/types/doi_item.rb
@@ -225,7 +225,7 @@ def fields_of_science
         {
           "id" => name.parameterize(separator: '_'),
           "name" => name }
-      end
+      end.uniq
   end
 
   def creators(**args)