It's a little odd, but you haven't used something like Ann, Lee, or Rose, have you? Those are pretty common middle names.

Sounds like she might have already thought of that name, couldn't remember if you used it or not, and even after finding out you had, decided they loved it too much to think of something else.

I'd take it as a compliment on your awesome name choosing abilities! Does your family and DD have much to do with her? (FWIW, we like one of the names of my cousin's DDs and given the difficultly we're having in choosing names, we won't be ruling it out based on that).

But I can understand that it seems a little odd...