My twin girls are now 15 months old. I have a few thoughts / ideas that may or may not apply:
1 -- Is this a recent occurence or have they never slept through the night? If it is recent, perhaps their teeth are coming in. We experienced night disruptions at about 9 months due to teething. It lasted a few weeks.
2 -- I realized that my girls had gotten into the "habit" of waking and wanting to feed -- rather than needing the nourishment. I learned this at about 4.5 months when they woke up crying for their bottle but then one fell back to sleep and the other started playing before I could warm the bottles. From that night on ("never go back" is advice another twin mom gave me), I did not feed them at that time and waited until their next feeding time.
3 -- Are you exclusively breastfeeding? If so, wow! and good for you! It is very difficult to exclusively breastfeed twins; I was not able to do so and had to supplement with formula from the beginning before I completely ran out of breastmilk at the 4 mo. mark. The only downside of breastmilk is that it doesn't stay in the babies' stomach as long. If you have introduced formula, perhaps you should try to give them formula at night. Maybe it will stay with them longer.
4 -- Do they constantly nurse during the day also rather than eat at regular times? Maybe working on an feeding schedule will help establish one at night too. Newborns generally need to eat all day long, but 9 month olds shouldn't need to "graze" so much.
5 -- For what it's worth, my girls have always eaten solids between 5 - 6, had a bottle and bath between 6 - 7, and gone to bed between 7 and 8. All of the sleep books I've read suggest that an earlier bed time (like 630 pm even) can help because keeping baby up too late makes her overtired which can lead to night waking.
In any case, hang in there. We all just muddle through as best we can. It is not easy, but having 2 little girls is just the best! And the first year is the hardest, so you're almost there.
If you have any questions (or need to commiserate ;o) )feel free to shoot me a note.