Im not sure how, but this person has been trying to find exploits in my forum board for a few days now... I have page after page of his different IP logs (from the proxies he has been using), and he has managed to create accounts with the same names, and he posted saying that he has apparently hacked me... Though i cant really see any evidence of this. If you want to see the duplicate username, then visit here:
http://www.cyb3rfr3aks.com/forums/memberlist.php
See how he has created another user called 'c3f3 Admin', when that is my admins account...
I have just upgraded to MyBB 1.6.3, will that fix the username thing?