If a rogue takes two weapon fighting and uses a light weapon in his off hand, when he performs a sneak attack does he add the sneak attack bonus damage to both weapons if they hit for that turn?
Sneak attack doesn't matter if it's a main-hand weapon or a off-hand weapon.
So, yes, assuming the target qualifies for sneak attack damage (flanked, flat-footed, etc) both weapons can do sneak attack damage if they hit.