Jacob had a problem with a foremilk/hindmilk imbalance, though it was mainly because I had too much milk rather than what he was doing. I expressed a little milk before he latched on, which would be about the same as letting the other twin nurse first. Also, since Jacob nursed all the time for just a few minutes, I used one side for 3-4 hour blocks of time. So if he nursed at 8:00 on the right and wanted to nurse again at 9:30, we went back to the right. I don't know how you're nursing twins, but I'm guessing you might be nursing them both on alternate sides each feeding. If that's what you're doing, this will work perfectly for you.
Are the poops very green and very powerful? That's the way Jacob's were. If he went while his diaper was off, it would fly over 5 feet away. There was something that blocked the path about 5 feet from his changing table, so we never figured out exactly how far they would go.
Unless you're planning on using bottles, either with formula or expressed breastmilk, I'd try every solution that doesn't involve a bottle first. Call your local La Leche leader. She'll have lots of ideas and the names of good doctors and lactation consultants in your area. A meeting would be great, too. Since so many women have had the same problem, you'll get tons of suggestions.
Good luck!