PREHEAT oven to 350 degrees and lightly spray a large roasting pan with vegetable oil.
Sprinkle the cavities of both ducks with salt and pepper and add the apples, onions and orange to each cavity and truss (or secure) with skewers.
Fold the neck skin under the bird and place breast side up in the roaster. Prick theskin ONLY with a fork. Roast, uncovered for 2 hours or until the drumsticks move easily.
Meanwhile in a stockpot, pour in the chicken broth and add the giblets and necks from the ducks. Add onion, celery and carrots, bring to a boil and simmer for 30 minutes. Drain the giblets, necks, onion, celery and carrots and reserve 2 cups of the duck stock. Discard the meat and vegetables.
Drain the blackberries and reserve 2 cups of the juice. Set aside.
Take the ducks out of the roaster, cut in quarters and set aside; covering with foil to keep warm. In the stock pot, loosen the brown bits and add the bits with two cups of blackberry juice, Cointreau, and duck stock in a saucepan.
Boil until the sauce is reduced in half, or approximately 20 to 30 minutes.
In a bowl, combine the flour, jam and butter and gradually add to the saucepan. Stir well until mixture thickens; approximately 10 minutes. Now add the blackberries and stir.
Turn the oven on broil and place the quartered duck pieces under the broiler until the skin is crispy. Place on a platter and serve with the blackberry sauce.
You may easily double the sauce if you wish.