I know this is repeat all over the place, but I'm curious, is there any actual evidence of them exerting dominance vs just not paying attention to what was sitting there first? I mean in the wild they find them in groups in holes and they are not forced to be there. Just seems to me like they just go w/e they want when it's bed time, despite another snake being there or not. I'm not calling you out or anything, I just see it repeated all over and was wondering if someone actually had some evidence or if it was just another runaway rumor.
However, I would never recommend someone to keep ball pythons together. There is zero advantage to it. You need a bigger cage than normal, which chances are two cages will cost less than one big one. You still buy the same amount of stuff you would buy anyway to go in the cage. People like to see it as saving money or space, but you really don't save much of either comparatively. Then you run into issues of how the actual snakes are going to take it. If any illness appears, which one has it or do both have it now? You have to feed outside the cage now and need some sort of container for the snakes to feed in (more space taken up). Will the snake actually eat outside the cage? I know I have a few who wouldn't.
It's not that you can't successfully keep ball pythons together. Just there is no advantage to it and many other risks that get tacked on because of it.