Didger 4
Didger 4 allows you to save and load calibration points to/from a data file. Calibrate the first image in the Image Registration and Warping dialog, click the Save button to save the calibration points to a file. When you calibrate the next image, click Load and load the previously saved data file.

Didger 3
You can load calibration points into a Didger 3 project from any other Didger project (PJT) file. For example, if you calibrate one image and save it to a PJT file - then when you import your next image and go to calibrate it, just click the "Load" button to load the World X and World Y coordinates from the other PJT file. If the coordinates are the same, you won't have to retype them.