There are many cases where filenames can generate problems, especially between different operating systems (e.g. Mac or Windows) or when transferring files to a webserver. In particular, spaces, special characters, or diacritics in filenames can be wrongly translated or even avoid file saving.
PitStop 2020 has a handy new feature. Using an Action List, it is now possible to overlay one PDF file onto another. Born from the Overlay PDF Action List is the Overlay PDF app available for free on the Enfocus Appstore. A related app, which is also free, is Split PDF Layers. Using a combination of these two, you can handle versioned PDF submissions in an automated way.