On Thu, 24 Jan 2019, Greg Newby wrote:
It is possible by comparing the full 2009 edition with a printed copy from 1923. It's not impossible, it is just extra work.
In this type of situation, it might be easier to obtain a 1923 printed publication and scan it.
If you have to have the original in order to prove that it's okay to scan the reprint, that essentially means that reprints are useless as a source of scans at all (barring edge cases like originals that you don't have permission to scan but do have permission to read). Relatively recently the Pulp Scans list has shared scans of Weird Tales reprints, including reprints that come from 1923 and have therefore just become public domain. Original Weird Tales from that year are very valuable and the chance that anyone's going to scan them all or even have them is negligible. It's going to be either allow scans of reprints, or lose those issues forever. (Weird Tales is also a good example of how Project Gutenberg's image policy is terrible, since it has ads and illustrations that won't get preserved without using high resolution.)