I got a user named 'Cake' and after shifting them to groups with moderator abilities, his username was displayed CakeCake on profile/postbit. However, at the 'Last Post' column, it was displayed correctly as 'Cake'. When I try to edit his username in ACP, it also displays 'Cake'.
Have you made any template modifications to the postbit or profile templates?
Nope
If I were to make it, it should appeared to all users instead of one, right?
Yeah, it would have. Sorry, I thought that's what you meant.
What happens if you edit the user's username in the ACP to make sure it's cake (You may have to change it to something else first, and then change it back again).
Tried it too
Lets say i change it to Sweets
It showed up SweetsSweets
Does this happen to anyone else in the user's usergroup?
Nope....he got a few secondary groups though.
And does it happen to any of the users in those groups?
How about if you make a test user and make it a member of the same usergroups, does it happen to that user too?
Did the same thing, and yes! It happened to that user.
Do you have any custom stuff applied to their username (like the code to make it Red, Green etc?). Sorry, I can neither remeber what it's called, or where it lives in the ACP but I hope you get what I mean.