An electrophotographic copying machine having duplexing mode of operation and first and second selectively enabled sheet supply stations. The first supply station has a feeding device which turns the copy sheet to be fed upside down before delivering it to the conveyor moving the copy-sheet toward transfer station. In the duplexing mode of operation sheets fed from the second station are one side imaged along the copy-sheet path and are collected in the first section. Then one side imaged copy sheets are fed from the first supply station and are imaged on the other side along the copy-sheet path. A storage tray with adjustable stops is provided in said first supply station to handle copy sheets of different formats.