diff --git a/app/services/subjects/copy_subject_service.rb b/app/services/subjects/copy_subject_service.rb
index 987dfaa4a..99f5dcdc5 100644
--- a/app/services/subjects/copy_subject_service.rb
+++ b/app/services/subjects/copy_subject_service.rb
@@ -177,7 +177,7 @@ class Subjects::CopySubjectService < ApplicationService
   def copy_challenge_questions_data!(challenge_choose, to_challenge_choose)
     challenge_choose.challenge_questions.each do |challenge_question|
       to_challenge_question = to_challenge_choose.challenge_questions.new
-      to_challenge_question.attributes = challenge_question.attributes.dup.except('id,', 'challenge_choose_id')
+      to_challenge_question.attributes = challenge_question.attributes.dup.except('id', 'challenge_choose_id')
       to_challenge_question.challenge_choose_id = to_challenge_choose.id
       to_challenge_question.save!
     end