At first glance, I thought you were naming real babies, and saw Mary Kate and Ashley and thought "please, no!" But for dollies, you can have lots of fun. ;)
Polly and Dolly? (my doll when I was little was named Polly the Dolly.) By the way, if these new ones match one she has already, are these going to be triplets? Like, Polly, Dolly, and Molly? :)
Is your DD going to let you have a say? My girls are very particular about their dolls names, and I don't have much to say about it! They often make something up. Merida Lalooda Champient was around for a while. Currently DD4 is talking about her "friend" (sometimes she's her teacher, too) named Marthy. :)