a sheet - fed offset printing press for printing multiple colors on both sides of sheets , preferably on sheets of paper , includes a first row of in - line printing units for printing a first side of the sheet , followed by a reversing device , followed by a second row of in - line printing units for printing the other side of the sheets , and followed by one or more varnishing units that are disposed in such a way , or include varnishing blanket cylinders that are disposed in such a way , that the front sides and the back sides of the passing sheets are varnished . a further reversing device is inserted between two varnishing units . a method of printing multiple colors on both sides of sheets is also provided .