When an admin wants to replace an uploaded global resource file it doesn't allow them to use the same filename, it appends with '(1)' on the end. This means any link to that file will be out of date, pointing to the original file.
For example, I have a Terms & Conditions PDF, I link to it from multiple courses, pointing to the global resource file url. I can't simply replace the file. I have to delete it and reupload to avoid '(1)' being added and the links being wrong.