I don't remember any specific examples from this forum, but on others I've seen the following (priceless) slip up:
Account A: why dont u shut the fcuk up u little pu$$y fag bich Account B: haha y dnt u m8ke me u buttlicker Account B: who r u calling a buttlicker u azzwipe Mod: Wait, what? Account B: ummm wait i mean i was joking i mean wait no hes hackin my accnt!!!!!
Edit: One of the clearest signs of multiple accounts (if you can't see an IP address) is if their posts are made 2 seconds apart. Every time.
Of course, if it actually were 2 people, they could just be really eager to call each other names.
Well, it is more like Multiple Personality Syndrome, from my understanding Schizophrenia can be where you have multiple personalities, but you can also see things. I just have two people inside my head.
I argue, he likes red, i likes green, he likes outside, I like inside, it is what I base my character off of, don't worry though, I got it under control.
I remember him, but I think I was actually on my hiatus during the height of his trouble. Otherwise I would have definitely remembered how and why he got banned.