My Doppelganger would be named Karok the Sane. While I am quite careful with what I say so I won't accidentally offend anybody. I'm very polite when I post and will very rarely swear and if I do I censor it. I'm also not very social and don't often post many forums. When I post something I try to give details so everyone can understand. Some of the things I might say may seem a little crazy, but that's why my username is Korak the Mad.
Karok the Sane on the other-hand would be very social but quite rude, obnoxious, and pretty unpleasant to have in the forums. They would also have a gigantic inflated ego. They would insult everyone who has a slightly different perception of the world and would rant and swear about how they were wronged and freak out over something that didn't go their way. They would overthink about everything and try and make everyone around them agree (So kind of like EternalNothingness. Sorry Eternal, just giving a similar example). They would be very vague when telling a story and not explain what they meant if someone asks and they would most likely insult the person asking. They may post something that won't sound a little crazy, but it will sound quite stupid and is most likely wrong.