Fnord
SasqWatch
This is very common, even more so in pen & paper RPGs. Most people seem to either play themselves (but better), or the person they want to be. You are a lucky person if your group contains more than one person who can drop their own personality and play something completely different.Even worse, I tend to play a more "extreme/idealistic" version of myself when I'm not playing my favorite stealth/archer type thing.
I've been able to play different characters than myself, but I just can't play an evil person. It goes against my very nature. Because of this, I find games that forces me to do evil acts, or act like a jerk to be hard to play (unless the games are humorous. I love Dungeon keeper, and shooting my friend in the back in Paranoia (pen & paper) is always fun).