Your second sentence is correct, the first, not so much.
When you think about it, Duel Wielding doesn't have to be over-powered. I mean, with one sword in hand, you have more focus on that hand, so naturally you could do more damage. What if you didn't get any necessarily powerful boosts to duel wielding until you've been using it for quite some time? You could start out not doing as much damage as 2 handed or 1 handed, but still have the ability to use it for the sole purpose of liking the play style. Or, maybe it could have the advantage of opening up more attack points.