I don't have any evidence, but I tend to believe that such incidents were caused by social stress in captivity, rather than a feeding response. Some snakes get along just fine with others, some stress out. I've seen it time and time again. Sometimes, I have to do some shuffling of the communal housing arrangements. It's important to learn how to spot social stress. If it goes on too long, things like cannabalism or physical health problems can arise just from mental / social stress among your snakes. Some snakes just don't get along with others and prefer to be alone. It's no different than say... people locked up in prison. Some just shouldn't be housed together. It's not because they can't get along with other people (or snakes) it's that they don't get along with the particular people (or snakes) they've been housed with.

If you don't spend any time watching them when they don't know you're watching, social stress can be hard to spot. Next thing you know, a snake is eating another snake. But I honestly believe it has nothing to do with being hungry.