Yes, similar names doesn't denote anything. My surname is incredibly rare, but there's two different spellings of it. I've seen that spelling with an artist who's worked for Marvel, and spoken to one on the phone in my old job in a call centre.
My cousin did some digging and we do all trace back to some Dutch immigrants that came to England to work on dikes. One group went south, one stayed in the North. Even so, I wouldn't class us as related.
Even ignoring that. Think how many Smiths there are.