@mentioning a username in VINCEComm discussions is ambiguous

[zmanion]

Describe the bug
@mentioning a username in VINCEComm discussions is ambiguous.

To Reproduce
Access a case in VINCE, draft a message in a discussion, @​mention someone, for a specific example, @​Steve (there appear to be more than one Steves). One of the Steves is selected, possibly the wrong Steve, and the wrong Steve may be notified about a discussion/message/case they are not part of.

Expected behavior
The dropdown selector would offer multiple choice of similar or conflicting usernames and/or VINCE overall would prevent the creation of duplicate visible usernames.

Screenshots
If applicable, add screenshots to help explain your problem.

Platform details
Recent/latest FF on macOS, have observed other users encountering the same issue, probably using different browser/OS combos.

[zmanion]

Further detail: @​person is part of the case, but a different @​person is selected. Not sure if this incorrect @​person is notified and they are not added to the case by the mention.

[zmanion]

It's possible this is only a display confusion issue with the mouseover after the comment is posted.