If neither testicle has dropped yet then he won't have viable sperm so he won't get a mare pregnant but he CAN raise hell trying and he WILL try. If it were me I'd tolerate it until there started to be a problem and then I'd tell the BO it's either him or me and I'd be prepared to leave.
There's nothing like the Rockies in the springtime... Nothing like the freedom in the air... And there ain't nothing better than draggin calves to the fire and there's nothing like the smell of burning hair. -Brenn Hill