All I can say is the the Selective Service operates an imperfect system. My son registered on his 18th birthday — took off work to do it. On his 20th birthday he received a letter like yours threatening him because he had not registered. A phone call fixed it.
Another friend of mine is a twin. He and his brother had the same names, except reversed. Frank Edwin Xxxx and Edwin Frank Xxxx. One was drafted for the Korean War and the other was never called.
If they would answer their darn phone. Can’t leave a message and the voice messaging system just kicks you off with the, “we are too busy to take your call. call back”. Blame it on Bush, the Sequester, and Republicans I suppose.