Two dogs wearing muzzles are running.
two dogs are eating
One can not be eating and while wearing muzzles.
The dogs cannot be running and eating at the same time.
The first sentence is about two dogs wearing muzzles. The second sentence is about two dogs eating. A dog cant be wearing a muzzle and eating at the same time because a muzzle is designed to keep the jaw shut, and you need the jaw to chew up food and therefore eat.  The second reason is that the muzzled dogs are running. Running and eating at the same time isn't impossible but highly unlikely because one, they are muzzled, and two, its pretty dangerous to run and eat at the same time.