OK, we're narrowing this down, but you still didn't answer all my questions.
Your post implies this only happens after you mixdown (bounce) to a single stereo track. Does this mean that when you listen to the mix before bouncing you are hearing things in both ears?
Also, there are multiple pan locations in Sonar's track view. For each track there are a couple on the FX tab for the busses, plus one on the Mix tab. Then there are pan sliders on the VMains and Aux Busses as well. Are they all centered?
So my next question is what VMain are you using as the OUT setting on your tracks? Is that VMain visible in your Track View, and if so, what is it's pan setting?
Oh, and one other thought. Is there a Left and Right input connection on the Rolls? Where are you plugged into? Usually on these things only one jack will work for stereo input (normally the Left). On second thought, I guess if it works OK with CEP under the same configuration, the problem is more likely to be somewhere in one of your Sonar settings.