I have twins too and for many months one would wake the other. It happens now too (they're 16 months) but usually only towards the end of a sleep period. What I think has helped us is a sound machine. My baby nurse bought it right away when the twins first came home from the hospital. You may have read that noise machines can help babies sleep. We bought ours at....I'm blanking...you know that specialty electronic, guizmo store at malls? It has 5 sounds. We use the white noise. I just bought one for myself too. The twins know when they hear that noise that it is time for sleep. In addition to drowning out each other it helps to drown out other noise too. Good luck.