Yep! They team up against the schnauzer female! 
In the instances they have not it was really IMHO more to do with their backgrounds-both have issues due to bad people.   
Scoobers play fights with me it freaked Elvis out and Elvis wigged out on Scoobers...we no longer do that with Elvis around or able to get to Scoobers.   
Elvis is unaltered Scoobers is the only other time we had drama was with a female in heat around...can't wait to have two altered males. But with no female in heat or any "protect mom" they're best buds actually.    
Scoobers didn't like other dogs touching him-he had severe dog aggression when I first got him once that was dealt with he still would growl get up and move if another dog tried to pack snuggle or lay down too close to where he was sleeping.I've since caught Scoobers letting Elvis snuggle him...he still will moan and move away from Princess.    I don't think the opposite sex coupling of dogs really is the rule of thumb but I cannot disregard the above as it's my experience. 
I'd just have both neutered.        |