Preheat oven to 375°F. In a large ovenproof skillet, cook bacon over medium-high heat until crisp and golden. Drain bacon on paper towels. When bacon is cool enough to handle, crumble and set aside. Pour off all but 1 Tbsp. bacon fat from skillet.
Add onion and garlic to skillet and cook, stirring, until onion is golden, about 5 minutes. Add cannellini and kidney beans, brown sugar, molasses, cola, tomatoes, dry mustard and crumbled bacon and stir to combine.
Cover skillet, transfer to oven and bake until mixture is bubbly and juices have thickened slightly, about 1 hour. Serve hot