Only 15 inches?
If the snake is only 15 inches long I would say that 2 fuzzies at once is wayyyy too much. How long after you feed him does he poop? Usually it takes around 2 to 4 days. If it's taking longer than that he's having a harder time digesting. My corn is 20 inces and she couldn't handle 2 fuzzies a week. IMHO, 2 is too much unless you are power feeding for a reason. Still, power feeding isn't good for them either.