Printing on both sides of the sheet requires additional work and time. We cannot feed a sheet of material into the printer and have it print both sides at the same time. This is due to the thick nature of our papers and they have to be straight-fed through the printer to prevent curling and bending. Due to this additional work involved, we have an additional cost for printing on both sides. This cost is shown and paid for up front when you place your order - these fees do not come later unless you did not purchase the correct options for your order.