If the orientation in which your original is placed is different from that of the paper you are copying onto, the machine rotates the original image by 90 degrees to fit it on the paper. This is called "Rotate Copy".
This function works when [Scale to Paper Size] is selected. For details, see Auto Reduce/Enlarge (Scale to Paper Size).
If you are enlarging A5 or 51/2 × 81/2 originals onto A4 or 81/2 × 11 or larger, place the originals in the orientation.