Scrolling down list of users in the "Assign Issue" dialog results in duplicate users appearing (Edge case)

Summary

This is the edge case of JRA-44113.
JRA-44113 has already been closed but the problem sill occurred in the following scenario.

Steps to Reproduce

1. Create 15-20 users, ensure all of them are able to be assigned issues (you need enough users to cause the user list in the Assign Issue dialog to have to scroll).
2. Assign 2-3 users you created in Step 1 to some tickets to make them appear in Suggestion section in the assignee list. (Please check this KB to understand how the suggestions are calculated.)
   Please make sure the 2-3 users are not in the end of All Users list.
3. Click Assign, then hit the dropdown arrow in the Assignee field.
4. Scroll down (using the keyboard or trackpad/mouse, it doesn't matter) to the bottom of the list.

Expected Results

You reach the bottom of the user list and there's no duplicates.

Actual Results

There are some duplicate in the user list.

Notes

• This isn't browser-specific (I can replicate it in Firefox, Chrome, and Safari)
• This problem is also reproduced when creating an issue

Workaround

Currently there's no workaround, but this issue is purely cosmetic.