Rub salt evenly over duck and refrigerate for chilled, about 30 minutes.
Heat oil in a large Dutch oven over medium heat. Add bacon to pan and cook 7 minutes or until crisp, stirring occasionally. Remove bacon from pan using a slotted spoon and set aside. Increase heat to medium-high.
Add lamb to drippings in pan and cook 8 minutes, browning on all sides. Remove lamb from pan, and set aside.
Preheat oven to 300°F.
Rinse duck with cold water; pat dry with paper towels. Add half of duck, skin side down, to pan and cook over medium heat 15 minutes or until golden brown. Turn duck over, and cook 10 minutes or until browned and fat under skin is melted. Remove duck from pan. Repeat procedure with remaining duck, then set duck aside. Discard duck fat, except for 1 tablespoons.
Add onion and pepper to pan; cook 7 minutes or until lightly browned, stirring occasionally. Stir in tomato puree and garlic and cook 1 minute.
Return lamb to pan. Nestle duck into lamb mixture then add broth and 2 cups water. Cover and bake at 300F for 2 1/2 hours or until lamb and duck are very tender. Remove duck from pan and let stand until tepid. Remove skin from duck; discard. Return duck to lamb mixture. Taste and adjust seasoning, if desired.
Increase oven temperature to 375°F.
Stir 2 cans of beans into lamb mixture. Add bacon, sausage, and duck then top mixture with remaining 2 cans of beans. Sprinkle breadcrumbs evenly over top. Cover and cook 1 hour and 10 minutes. Uncover and cook an additional 20 minutes or until browned and bubbly.