I have lovely identical twin girls who are now 2yr 2mos. We are in the depths of the terrible twos but our main problem at the moment is sleep. Our younger twin lies in her cot, moaning constantly - she doesn't sound distressed, it's just a constant "Aaaaaaah, aaaaaaaaaaah" - both before she falls asleep and if she wakes up in the middle of the night. It's loud enough to wake us in the next room.
The girls used to be excellent sleepers but now they wake us at least once every night and sometimes lie there moaning for over an hour before going down for their afternoon nap. It's driving us crazy.