Abstract: A printer has dual opposing printheads which can print in tandem on two sides of paper fed along a printing plane. The dual opposing printheads can print the same information on each side of two paper sheets fed in back-to-back (two-ply) fashion, thereby providing a document and copy simultaneously. The printer can also print different information on two sides of the same paper sheet or on each side of two paper sheets, thereby doubling the printing speed as compared to a single printhead. In a preferred embodiment, the dual opposing printheads are mounted in carriages driven reciprocatingly in tandem by one drive belt. Tandem paper feed mechanisms are arranged at one side of the printer and have respective clutch spring devices which are actuated alternately by cam surfaces on the printhead carriages so as to drive a pair of paper feed rollers with the paper fed in between them.