Desio988 wrote this on vampirediaries.net and i think they makes some good points. Stefans not copying Damon. Paul isn't copying Ian. They are both amazing actors with different approaches/styles to different characters.
Sidenote: Does anyone remember the episode in season 2. Where STEFAN had the room full of girls to feed on? That was Stefan's thing, not Damons.
k, everything I'm bout to say, has a perameter. The parameter is....when they are evil. So only concentrate on when they are evil. Not when they are good.
They have two different approaches to this "being bad" thing. Here's the reason why....