L.B.
If they are napping still, which they should be, DON'T eliminate it! Overtired children have a harder time falling asleep and wake more frequently that kids who are getting the sleep they need.
I had a similar problem with my then 2 year old, and bought a great book called 'Healthy Sleep habits, Happy Child' (I got it on Amazon.com)( he had never slept through the night without waking)
The technique he describes for 2 year olds is this;
(start this on a Friday night, or whenever you don't need to get up early the next day)
Explain to your twins that they need their sleep and so do you, and that things will be changing from this night forward.
Do their normal bedtime routine (maybe even start a little earlier than you normally do) and then when they are ready to sleep, turn out the light and walk out of the room. When one of them pops out of bed, calmly walk them back to the bed and put them in. Here's the important part: DON'T SAY A WORD! You have to be absolutley silent! Not angry or disapproving, but silent, like it's no big deal. The first night I tried this my son probably got out of the bed 30 or 40 times, with every excuse in the world why he had to be up (and crying, etc). I never said a word to him, just returned him to his bed. I stood outside his room where he couldn't see me, but I could hear him when he got out of bed and was able to quickly get him back in bed once he made it out of his bedroom. Eventually he fell asleep from shear exhaustion! This was the first time in his life that he had ever fallen asleep on his own. The next night, he got out of bed twice, shortly after I put him to bed, then slept through the night.
I don't remember if there was a special section for twins in this book, but buy it and read it! In the meantime, try what I suggested and within a few days they should be sleeping better.
Good luck!