The cricket team I played on years back had 2 Pauls. Both were a similar age, height and build. But one had a double-barrelled surname, so he was known as Paul Two-Dads, and the other Paul was Paul One-Dad. Later they just became known as 2 Dads and 1 Dad.
perhaps doesn't work so well if like me, you have a standard popular name from the 1970s, along with about five others in your school year