To prepare sourdough starter for rye dough: Start the day before you plan to bake the bread. Stir yeast into warm water in a medium bowl. Set aside until foamy, about 5 minutes. Add both flours; mix them into the yeast mixture with your hands until incorporated. Cover bowl loosely with plastic wrap and set aside in a warm place overnight. To prepare pumpernickel starter: Start the day before you plan to bake the bread. Stir yeast into warm water in a medium bowl; set mixture aside until foamy, about 5 minutes. Add both flours and stir until combined. Cover bowl with plastic wrap and allow to sit at room temperature overnight. To prepare rye dough: Stir yeast into warm water in a large bowl; set aside until foamy, about 5 minutes. Add reserved rye starter; stir to blend. Add salt, 2 tablespoons oil, sugar and caraway seeds; mix well. Gradually add all-purpose flour and 1 1/2 cups rye flour, mixing with your hands until a stiff dough forms. Turn dough out onto a lightly floured work surface. Knead until dough is smooth and elastic, about 10 minutes, adding more rye flour if needed. Generously grease a large bowl with remaining 1 tablespoon oil. Form dough into a ball; add to bowl, turning to coat with oil. Cover bowl loosely with plastic wrap. Set aside in a warm place until the dough has doubled in volume, about 1 hour. To prepare pumpernickel dough: Pour warm water into a large bowl; stir in yeast. Add pumpernickel starter along with coffee, molasses, wheat bran, rye flour, cocoa powder and brown sugar. Mix well. Add 6 cups whole-wheat flour and salt. Mix until a stiff dough forms. Turn dough out onto a lightly floured work surface; knead until a smooth dough forms, about 10 minutes. If dough is too sticky, knead in remaining 1/4 cup whole-wheat flour. Grease a large bowl with oil. Add dough, turning to coat with oil. Cover bowl loosely with plastic wrap. Set aside in a warm place until the dough has doubled in volume, about 1 hour. Sprinkle a large baking sheet with cornmeal. Return both risen doughs to a work surface. Divide each in half Push each half of dough into an 8-in square. Place 1 square of pumpernickle dough on top of 1 square of rye dough; roll up doughs together, tucking the ends underneath and shaping the combination into a round. With both hands, roll the round back and forth, flattening and shaping it into continued in part 2