I was once un-banned from the old 606 after being temporarily accused of having two accounts. I'd gotten a bit bored of forums in general and had decided to delete my account. After a while I decided to come back and re-registered under the same username. A while later I was banned on the grounds of having two accounts.
Apparently if you decided to delete your own account it didn't show up on their system as the account being being cancelled. Once you were registered it kept your registration active. Forever. I had a hard time convincing them that I hadn't been banned the first time around and that it was me who'd deleted my own account.
Could anything like that happen here if someone came back?