Abstract: The present invention is an apparatus and method for duplex printing of a sheet-like substrate in a continuous single-pass flat printing process. The device comprises a first conveyor unit in communication with a feeder and a second conveyor unit in communication with a delivery. Each conveyor unit has a printing device and a drying/curing device disposed adjacent to the conveyor unit for applying a printed material to the substrate. A transfer device is disposed between the two conveyor units for transferring the substrate from the first conveyor unit to the second conveyor unit and turning the substrate, thereby allowing both sides of the substrate to be printed. Alternative embodiments may include any number of conveyor units and transfer units.