I have seen a couple of them Fiona so im not sure if it is as rare as we think .
Two-headed snakes do not have a long life expectancy, particularly in the wild. Each head has a brain and, usually, some control over the shared body, and the two cannot communicate with each other. Movement is therefore difficult, as each head may try to travel in a different direction, and in the worst case scenario, the heads may fight or try to eat each other.
Some two-headed snakes share a stomach, while others have a stomach for each head. In a two-headed snake with separate stomachs, one of the heads may die if it routinely loses fights over food. Even if there is only one stomach, two-headed snakes may not be able to capture prey if the heads are competing for food.
Little more info for you Fiona .x