For stuffing, in small bowl, stir together crumbs, onion, horseradish, 1 teaspoon caraway seeds and 1 teaspoon brown sugar. Add 2 tablespoons beer; toss to mix.
Untie roast. Pat stuffing mixture on one of the loins. Place second loin on top; retie to secure. Place in shallow roasting pan. Season with salt and pepper. Roast in 350 degree F. oven for 75 -90 minutes or until done, internal temperature reaches 155-160 degrees F. and meat is just slightly pink in center. Remove roast from pan.
Deglaze roasting pan with 1/2 cup remaining beer. Strain into small saucepan. Stir together water, cornstarch, bouillon granules, 1 teaspoon brown sugar, Worcestershire sauce, and 1/2 teaspoon caraway seed.
Stir into beer in saucepan. Cook and stir until thickened and bubbly. Slice roast to serve with sauce.