body path is permitted and processing to resume the transport via this path is executed further when paper is detected at a specified position along the inhibited transport path position immediately before the junction of the main body path and the dup path the transport operation is discontinued every time a paper sheet is discharged from the machine the oldest of the items of effective paper data as to the sheets fed from the dup feed outlet is nullified further every time a sheet is placed into the dup tray 25 the feed counter 2 is decremented and the oldest of the items of effective paper as to the sheets fed from the main body feed outlet is nullified depending on the presence or absence of paper in the dup tray 25 a dup presence flag is made 34 1 34 or 34 0 34 when jam resetting is effected with a duplex print remaining within the machine before being discharged therefrom and with a simplex print present in the dup tray 25 an alarm is given to this effect and usual jam correction processing processing for indicating the specified number of copies and the number of return documents is thereafter executed furthermore all paper data is reset the process except for the foregoing processing procedures is collectively shown as a step for example a sequence of copying operations is controlled when the copy mode key 54 is found to be on edge change in state from off state to.