HEAT oven to 350°F.
COMBINE flour and baking soda. Beat butter and sugars in large bowl with mixer until blended. Add eggs, 1 at a time, mixing on low speed after each just until blended. Gradually beat in flour mixture until blended.
DIVIDE dough in half; place in separate bowls. Add melted chocolate to dough in one bowl; mix well. Add chocolate chips when cooled. Add peanut butter to dough in second bowl; mix well. Stir in peanut butter chips.
PLACE 1 tsp. of each flavor dough, side-by-side, on baking sheets, leaving 2 inches between doughs for each cookie.
BAKE 8 to 10 min. or until lightly browned. Cool on baking sheets 3 min. Remove to wire racks; cool completely.