Isn't that lovely? You are not alone. Mine doesn't try to eat his own but he does try to eat our other dogs. There are a number of reasons why they do it. If they are lacking nutrients in their diet, to hide it if they think they are being bad or boredom to name a few. I make an ick noise when he approaches it and tell him what a good boy he is when he leaves it alone. He's getting better - I think they may grow out of it too. You can purchase products to add to the food that makes it distasteful.
It really makes you rethink puppy kisses.
Or appreciate a good tooth brushing!