Graphic editing software

This work around is possible because GIMP supports layers and that you can export your file as a MNG file (Multiple-image Network Graphics).

This idea is to open your PDF document with GIMP, it will results in one page per layer.

Then, add to each page the edit that you would like to perform, for example like adding your initials to the end of each page.

Then revert the order of layers, as you will need them to be in revert order to get the final result.

Then save this document as MNG file.

Then open a terminal and perform the following line of code: convert your-file.mng results.pdf, you should then end up with your multiple edited PDF document. Note that if you face an error during the conversion process, just look for the error code on the search engine, you will find quick fixes.