I can't decide. I love both, but today I'll have to go with
Natalia. I prefer
Natalie and
Natalia in both cases. I say it Nah-TAH-lee-a.
No, I don't think either is too common.
As a combo, it sounds off. I'd go with either
Estelle Natalia (love this) or
Estella Natalie (still doesn't sound great.)