In a large skillet, brown ground beef, onion and green pepper until meat is no longer pink; drain.
Meanwhile, divide one loaf of bread dough in half. Press over the bottom and up the sides of two 9-in. greased pie plates. Sprinkle each pie with 1-1/2 cups mozzarella cheese. Divide beef mixture and spoon over cheese. Top with pepperoni and mushrooms.
Divide remaining loaf of bread; form into two 10-in. circles. Cover each pie with dough; crimp edges to seal.
Spread half of the pizza sauce onto each pie. Sprinkle with remaining cheese. Bake at 400° for 25-30 minutes.