A dual mode stapling system with a first mode for plurally stapling a set of sheets parallel to one edge and a second mode for corner stapling at an angle to a set of sheets, with a single stapler mounted for linear movement by a simple linear repositioning system to selected stapling positions, but selectively further movable by the same linear repositioning system into a transition area where the stapler is automatically pivoted into the second stapling mode for corner stapling by a camming member which engages and pivots the stapler. A spring automatically reverse pivots the stapler back to the first stapling mode position when the linear repositioning system is reversed. The linear repositioning system may be a single reversable stepper motor driven leadscrew.