Lay the puff pastry sheets out on a flat work surface. Split the sausage casings lengthwise and turn the mild sausage meat out onto 1 pastry sheet and the hot sausage meat out onto the other pastry sheet. Gently pat the meat out to fit the pastry sheets, being careful to leave a 1/2-inch strip bare on both long sides of each sheet. Top with 3 tablespoons of Romano and 5 basil leaves per sheet. Starting with 1 of the bare strips, roll the pastry tightly around the filling. The bare strip on the far end will stick to itself.
Place the rolls in the freezer for at least 1 hour; they should be just frozen enough to make slicing easy. (The recipe can be made to this point 1 week in advance.) Slice the rolls into 1/2-inch pieces, place on baking sheets and place in the oven for 20 to 30 minutes, or until golden brown. Remove and let cool 5 minutes before serving.