The unit test included in this issue is sufficient to verify the fix, and the other unit tests are enough to verify there are no regressions. If you really want to test manually: Create a quiz. Add a true-false question. Attempt the quiz as a student and submit it. As teacher go and review the student's attempt. Use the 'Make comment or override mark' link to add a comment "Comment 1" Use the 'Make comment or override mark' link a second time, and change the comment to "Comment 2" Verify that In the 'Response history' table under the question, verify that you can see both comments in the history. (Before this change, both comment actions in the history would be shown as 'Comment 2'.