Hi,
I feel your pain, I have thirteen month old twins and my friend who has almost three year old twin boys told me she is experiencing exactly what you are going through. As a result, as soon as mine turned one, I separated their bedrooms, my daughter was screaming (she went to the new room) as soon as we left her for the first three days, then her new routine kicked in, night night to brother, and daddy, baby einstien lullaby CD and book, then hugs and kisses from mommy and I was out the door, she awake in her crib, first 19 minutes, second night 12 minutes, third night 4 minutes, by the fourth night she seemed happy to see us go.
It is never too late to separate rooms if you have the option, they play together all day they don't need to sleep together to be close.
If you don't have hte option, my advice is to make sure your kids know how to fall asleep on their own, rather than being put to sleep, if you knwo what I mean. I would tell them abpout the importance of respecting other peoples sleep, why we speak quietly and don't wake a sleeping person. and pray that they stop, or at least if they wake each other up, they know how to put themselves back to sleep. Good luck.