I'm not good at searching for names, but I remember a lovely book by Erich Kästner about a pair of identical twins named Lottie and Lisa. They even made a film, I think it was called "The Parent Trap", although the twins there had other names. Well, this is the first suggestion, let's see what others have to propose!
I really mean it - I lay awake at night thinking about names! Sonny and Cher would be okay for a boy and a girl, or Ying and Yang .... my imagination isn't working too well these days, it seems!!