I had this problem shortly after I got Bus, after he and Annie started to be "friends". Their first meeting didn't go well due to my coworker not following directions and essentially facing them off- of course they wanted to brawl. When I reintroduced them, I impressed upon them to leave each other alone, and they were happily indifferent to each other for a good while (month or so?) before they decided they actually liked each other. When they first started engaging each other in physical play, it invariably ended in a tussle. Luckily Bus' teeth are more or less flat due to his tennis ball and rock fetching, as he's a good bit bigger than Annie.
I just managed them (either by preventing altogether or intervening when things started to simmer) to avoid the scenarios that would cause them to fight (rough play, play where one dog was looking less than enthused, any sort of tug or toy "sharing"), and they eventually (6 months or so later) developed a better understanding of each other's signals and earned more freedom. There were still some no go things like tug- Bus is a little bit insecure about his things around other dogs, and he takes that sort of intense eye contact and "fight" from another dog over a toy too seriously. They would frequently play "bitey face" without incident, and could play fetch together, though I tried to throw so as to keep them from arriving at the toy at the same time, or use multiple toys. These days Bus is too rough for Annie, but she'll play with him briefly on occasion, and if she corrects him, he backs off appropriately.
I would probably lean toward not letting them reach the point of fighting, as I prefer for my dogs not to practice that behavior because it can become more intense/easily triggered, particularly with same sex dogs. I probably err on the side of too cautious though, as I've also had a dog who thrived on creating conflict with other dogs and would cause serious injury, so prevention was key to preserving what dog interaction she could have- easier to prevent the fights than deal with the aftermath IME.
I know you were having issues with Pax RGing toward your roommates dog, and it's possible that that could play into the conflict, even though the RG of his food/your room has resolved- dogs can and will assign value to the most random things- locations, people, items, space, and it may not happen consistently (he may be ok with the other dog roughhousing near you unless the stars are aligned or dog is also doing ____). It may not be a factor, but it's worth watching out for. Bus will sometimes RG people slightly by getting between another dog and the person, then engaging the other dog in (sometimes rough) play until they back off. He's never entered the realm of aggression, but the fact that this is the ONLY time he plays with these dogs is telling. I don't make a big deal out of it as frequently the other dog is a willing participant, but don't let him do it ON me and often will make him get down or get on my other side so the other dog can get attention without him being obnoxious.
I would make it a point to closely watch their play and see if you can determine the trigger of the fights, so that you can manage accordingly to prevent them in the future. If you can identify it as only "X" scenario, that will allow you to give more freedom than if it's "sometimes when they play". In the meantime, make sure you are separating when you can't supervise, as you don't want them having a serious fight when no one is there to break them up.