Just wanted to add my 2 cents. It seemed to me that in prior versions of DO when I would search for duplicates across folders by checksums that the results returned were ordered by the way the directories were included in the initial list to search across. If you listed three directories (XXX, AAA, RRR) you would get your duplicates of a single file with all dupes in XXX, then AAA then RRR regardless of the file name.
file r in XXX
file t in XXX set for delete
file t in AAA set for delete
file p in RRR set for delete
file t in RRR set for delete
All the above would be dupes of one another but it was never random as to how they displayed.
That seems to have changed!
Today when I did a dupe finder, sometimes I would get the RRR first even though there were dupes in AAA and XXX which used to be listed first or as I said by the order the directories to be searched were added. I know this use to work because I typically would compare a new directory against several older directories and as long as I setup the new directory (I can't remember anymore if it was first or last) it would always auto delete the newest files and I wouldn't have to time going through them.