Thanks, @vanessahampton :) Sometimes I'm pretty sure that they signal to each other that it's the other one's turn to be awake. The timing is amazing!

Btw, I read your story about Precious and Phoebe last night ... it was amazing! I was working on a comment and then the clock struck 10. Both babies wide awake and needing my attention. So the comment was forgotten. But I did want you to know I really enjoyed it!