Drain cherries, reserving 1/4 cup of syrup. Set aside.
Place duck between 2 sheets of heavy-duty plastic wrap; flatten to even thickness, using a meat mallet or rolling pin. Sprinkle 1/4 teaspoon salt and 1/2 teaspoon Chinese five-spice powder over duck breasts. Heat oil in a large nonstick skillet over medium heat. Add duck; cook 7 minutes on each side or until done. Remove duck from skillet. Set aside, and keep warm.
Add shallots to pan and cook, stirring constantly, 1 minute. Add 1/4 cup port wine to skillet, stirring to loosen browned bits. Simmer 1 minute. Add remaining 1/4 cup port wine, 1/4 cup reserved cherry syrup, chicken broth, remaining five-spice powder, and remaining 1/4 teaspoon salt; simmer 10 minutes. Add cherries, and simmer 2 minutes. Add duck, and simmer 1 minute.