Their last names.
You tell your Wife, "I saw a lady, looked exactly like you" Wife asks, "WAS SHE BEAUTIFUL?" You cant say 'NO' You cant say 'YES' That is Checkmate!
I haven't seen you for a year!
Both their first names have six letters. That's it. For now. Edit: they're both dead.
Tyrone, Tyrone, Tyrone, Tyrone, and Tyrone. How did she tell them apart She called them by their last names!