Recently a script was written that attempts matches up Page: 's for a given Index:/File: with the original or hi-res scans available for that work at an external site, such as Internet Archive or Hathi Trust

However, in a small number of instances, the file/scans at an external source and those on Commons, have different layouts, as files on Commons (or Wikisource) have been patched locally to account for absent pages, or pages where pages-scans were too unreliable for accurate transcription/proofreading.

This means that the script used at Wikisource, can sometimes retrieve what is perceived to be the 'wrong' hi-res scan compared to a transcription for a given Page:

Ideally, information concerning these discrepancies of layout, should be recorded somehow, so that Page:s and scans can potentially be "re-matched" based on knowing where the Commons file's layout (and that of the Wikisource Index) and that of an external source differ, on a per file basis.

I had an example schema in a comment here :- https://en.wikisource.org/w/index.php?title=Index%3ARuffhead_-_The_Statutes_at_Large_-_vol_8.djvu&type=revision&diff=10959161&oldid=10614535