Prepare grill or broiler.
Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add bell peppers and onion; sauté 10 minutes. Add pasta sauce, and cook 1 minute or until thoroughly heated. Keep warm.
Remove casings from sausage. Combine sausage and turkey in a large bowl. Divide mixture into 6 equal portions, shaping each into a 1/2-inch-thick patty.
Place patties on a grill rack or broiler pan coated with cooking spray; cook 4 minutes on each side or until done.
Place 1 patty on bottom half of each hamburger bun; top each patty with 2/3 cup bell pepper mixture, 2 tablespoons cheese, and top half of each hamburger bun.