you will not find many reports of cannibalism heck many ppl dont even take their snakes to a vet if something is wrong with them.
just because multiple snakes are found in in the same burrow does not mean they went there because of the other snakes. perhaps the place in the burrow is the only place that has the correct temps and humidity for those animals. not to mention that alot of the videos you see are taken during breeding season.
Qt after the fact does not mean that the other one does not have something wrong with it also.
ppl use tubs because its the easier to keep, clean, saves on space. there is many reasons really. are you sure your snakes want to travel around? are you sure they dont prefer to be alone? are you sure they are not fighting for the same heat zone?