MyBB Community Forums

yesterday night one of my friend tried to upgrade our forum but he forgot to disable some plugins . everything was good until performing Queries section he got a message like below :

Fatal error: [SQL] [1062] Duplicate entry 'فراحمدی' for key 2
ALTER TABLE mybb_users ADD UNIQUE KEY username (username) in /home/manva3/public_html/forum/inc/db_mysql.php on line 548

as far as i know and recently consider it happen when there are same user and we should delete these user. is it true or not?
Please help me

There is already a thread on this. We do not need two.

http://community.mybboard.net/thread-47049.html