Baby names ????

Does it matter if someone else used the name cause if it's a boy I want to name him Christopher but my husbands best friends son is named Christopher and for a girl I like the name Elizabeth but my husbands ex wife's step daughter that's her name . I've liked these names since I was little and it sucks cause he says we can't name our kid either of those because somone close to us already used it . Let me know what everyone else thinks