A document reproduction machine operates either in a simplex mode (each copy has an image only on one side) or in a duplex mode (copies have images on both sides). In the duplex mode, an interim storage unit stores partially completed copies (only one side of the duplex copies have an image). A second copy run completes the duplexed copy production. For an odd number of originals, at the end of a duplex copy run, the last-produced copy set resides in the interim storage unit. In one aspect of the disclosure, in response to an indication of the end of a duplex run, the machine automatically transfers the last-produced copy set from the interim storage unit to a copy output unit. In another aspect of the disclosure, any change between simplex and duplex modes actuates the machine to empty the interim storage unit.