Preheat oven to 350°F (175°C).

Cook bacon in a skillet until crisp. Remove bacon and set aside, reserving some bacon fat in the skillet.

Add chopped onion to the skillet and cook until softened.

Add hamburger to the skillet and brown, breaking it up with a spoon.

Drain excess grease from the skillet.

In a large bowl, combine pork and beans, drained kidney beans, drained butter beans, catsup, brown sugar, sugar, vinegar, and dry mustard.

Add the browned hamburger, cooked onion, and bacon to the bowl and mix well.

Pour the mixture into a greased 9x13 inch baking dish.

Bake in the preheated oven for 1 hour, or until bubbly and heated through.

Let stand for a few minutes before serving.