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.
We actually do already have a Molly. I packed her away one day when I decided we had too many dolls. We started with one, Barb. She was one of twins at an op shop and i split up the family (dont get me started on the guilt i feel for having done so) DD1 got very attached to Barb. I assume it was because of Barb's abandonment issues, or her sadness over the loss of her brother, Bob. We went back to the op shop to get Bob, but he was already gone.
Anyway, DD was very attached to Barb, and I was a bit worried we'd lose her. So started the search for another. My MIL found Molly (affectionately nicknamed Moll) in an op shop. Then two more similar. Then another. Then or DDs 2nd birthday she got a doll that she named T-Pain. Like the rapper. She chose it out of a book.

TLR Yes, we have lots of say in what the babies are called. Requires mild deceit, but I'm okay with that, for the sake of laughs.

And no to Royal Baby name stealing! I'm quietly hoping that my DD's name gets a look-in. Or mine.