I've been to a lot of smaller pet shops over the years and have seen this several times. Most owners tell me that they aren't in there together long. As far as cannablism is concerned yes it can happen but its like finding a needle in a haystack unless of course you place a kingsnake inside that tank.. then the corn snakes would disappear. As far as the other eating each other it could happen but very rare case. Its a common occurance in smaller type pet shops who don't have the housing space but have the need. Petco and Petsmart have similar issues.. A good rule of thumb is like others mentioned don't buy from them.. Make them get more tanks or less snakes. Or maybe get a job at the pet shop and inform the owner of why its not a wise idea and become responsible for the care. I did that when I was 19.. worked at a small pet shop as the reptile handler and care taker.. Love getting paid for caring for reptiles...