Or have the inside testicle removed when he is older and leave the other one, even if you don't plan on breeding him. He will still be a male dog.
It makes me wonder why the females of such litter don't get a note on their pedigree/registrations. They after all will be carriers for this genetic problem.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015