My MIL's cousin has four kids, and three of their names are on our list- Thomas (which we will almost definitely use, it's my grandmother's maiden name and we love it), Charlotte, and Louisa. I don't think it would be THAT big of a deal to use one of the same names, but would it be strange if we used more than one? I'm in love with Louisa if we have a girl, maybe even as a MN.
If it matters, they live in the same city (really close to us, actually), but we don't see them super often, maybe every few months at a grad party or casual family thing. It's not like they'll be running around together at Christmas or anything though.