Place blackberries in a food processor and pulse until pureed.  

Heat 1 tablespoon of butter in a sauté pan or saucepan over medium-low heat.

Add the shallot and sauté, occasionally stirring, until they are tender and translucent, about 7 minutes.

Add the red wine and lemon juice.

Bring to a boil, then lower the heat and simmer until the mixture is reduced by about half.

Combine the puréed blackberries and the jam or preserves, pepper, and salt and add to the wine mixture.

Bring to a boil, then reduce the heat again and simmer for 5 minutes.

Stir in 1 tablespoon cold butter.

Set aside.

Season duck breasts with salt and pepper on both sides, more heavily on the skin side and lightly on the flesh side.
Preheat oven to 400 F

Place duck breasts, skin side down, in a large, cold oven safe sauté pan. Place pan over low to medium-low heat. After about 4 minutes, the fat should begin to gently bubble.

Remove pan from the stove and place in the preheated oven until internal temp reaches  130°F on an instant-read thermometer for medium rare, about 6 minutes.  For medium, continue cooking until duck registers 140°F for medium or 155°F  for well-done. Remove duck from pan and set aside to rest for 10 minutes.  Slice on a diagonal and spoon blackberry sauce over top.  Garnish with fresh blackberries.