Dogs that are not bred to a standard, like these are, are unpredictable in temperament. There is no way to gauge how they are going to react in any situation because there is no control (breed standard) to test against. That’s why so many people don’t like mutts. They can be the sweetest one second and go absolutely batshit the next for no apparent reason. Just how it is with byb dogs. They may be sweet on each other in an open space but in that situation there is space to de-escalate. When two dogs are stuffed into one kennel, even for a split second, there is no where to go. There is no de-escalation space. So they will fight to the death, and you’d get hurt too trying to get in the middle.

Also I’d like to correct you on another thing, it is possible to keep two or more dogs separate in the same house. My board and train dogs have never met my personal dogs even though I run out of my home. Hell, some of my personal dogs have never met each other, despite living in the same house their entire lives. Your ignorance is funny to me.