Stool eating is not a very delicate subject, but it can be a real problem if your dog gets into this habit.
Most commonly seen in winter and younger animals, stool eating is thought to stem from early inherited behavior of wild dogs who often suffered nutrition deficiency in times of game scarcity. They could gain nutrition from about 10% of the quantity eaten.
This behavior is also encouraged by the feeding of "cheap" dog foods which are poorly digested and still contain large amounts of undigested nutrients when eliminated.
Beside the offensive nature of stool eating in general, dogs become infected with many types of worms by ingesting food or water contaminated with round worm, hook worm, or whip worm eggs. So stool eating should be discouraged at all costs.
To solve this problem, remove the temptations by keeping all dog piles cleaned up immediately. If the pup might still find a way to eat his own or his companion dog's leavings, use Potty Mouth sprinkled onto the food eaten by the puppy(s) to give the resulting fecal material a taste that dogs dislike.