Crumble The Ground Beef And Italian Sausage Into A Large Skillet. Cook Over Medium-High Heat Until Browned. Drain. Combine The Ground Meats, Marinara Sauce, Mushrooms, And Tomatoes In A Slow Cooker. Cover, And Cook On Low Heat For 7 To 8 Hours. Stir In The Tortellini, And Sprinkle The Mozzarella And Cheddar Cheese Over The Top. Cover And Cook For 15 More Minutes On Low, Or Until The Tortellini Is Tender.