Owners of multiple snakes typically keep them all separated, as most snakes live alone and don’t really play well with others. In addition to one trying to cannibalize the other, they may also fight over food.
Medusa is an Albino Honduran Milk Snake who exhibits axial bifurcation: she has two heads who have independent thoughts and are each able to control the length of the shared body. This is caused by an incomplete splitting of monozygotic twins.
While it seems like [the two heads] would get fairly used to one another, they still don’t have the realization that it’s okay for one snake to eat, because the nutrients will be shared.
Each brain gets the hunger signal, and each decide they want to go for food. If one side has food and the other doesn’t, the two may begin to fight over it.