RE: Help me figure out what went wrong
I don't know if they would fight each other, But if they are on a Y harness the bad wires could cause a signal issue. It could make them both go full deflection and cause the snap. If they are on separate channels this would be much less likely. But would this strip the gears??? I would look more toward rudder flutter. The one servo with the bad wires could have went dead putting all the load on the other servo. The high speed pass could have over loaded it and let it flutter. While a hard hit can strip servo gears it's not common on a rudder. I would think they were stripped before it crashed. If they were stripped prior, than what stripped them? Even if one servo were strong enough to strip the other one, that's only one set of stripped gears not two.
Just my humble opinion.
david