I have now made some progress on identifying the causes of my endnote lists in RM8 being much longer than in RM7 for the same report.
In the first place, if you Memorize a citation in RM8 and Paste/Copy it rather than doing a Paste/Reuse, the citation cannot be reused by the Reuse Duplicate Endnotes option in reports. The option is not looking at the text of the endnotes to see if they are duplicate. Rather, it is looking at the internal table structure of the RM8 database. If the citations are separate citations in the RM8 database, they are not reused by the Reuse Duplicate Endnotes option in reports even if the citations are otherwise identical.
In the second place, otherwise duplicate citations come into RM8 from RM7 in the Paste/Copy state rather than in the Paste/Reuse state. Therefore, it is really important after importing an RM7 database into RM8 to run the Sources => THREE DOTS => Merge All Duplicate Citations process. This process converts all citations that are truly duplicate in all respects from the Paste/Copy state to the Paste/Reuse state.
I have been running the Sources => THREE DOTS => Merge All Duplicate Citations process every single time I import my RM7 database into a new RM8 database ever since the beginning of the RM8 Community Preview. Nevertheless I still have lots of citations that cannot be reused by the Reuse Duplicate Endnotes option in reports.
What is happening is that sometimes citations that appear to be duplicate will not merge automatically because of very subtle and sometimes invisible differences in the citations. They can be forced to merge on a one citation at a time basis in RM8 by the Sources => Citations => THREE DOTS => Merge Citations process.
There are several problems with doing it this way. One is that I have to redo it every time I import from RM7 into RM8, which is still several times a week for me. A second is that I have lots of citations that have this problem. A third is that you are almost merging blind. You have to do a lot of slipping and sliding in the sources => Citations => THREE DOTS => Merge Citations process to find out where the “almost duplicate” citations are being used. Even with the slipping and sliding, sometimes it can be very hard or even impossible from the RM8 user interface to see what the differences really are.
I suspect that such minor differences don’t really matter. If two citations that won’t merge automatically are so similar that you can’t tell the difference, your best strategy is probably just to merge them and to ignore any invisible differences. But for the time being, my strategy is to use RM8 to identify citations that won’t merge and to make whatever changes to the same citations in RM7 are necessary to make them merge automatically the next time I import them from RM7 to RM8. I will post more details about my process for cleaning up my citations in RM7 in a future message.
In the meantime, I should report that the Reuse Duplicate Endnotes option in RM8’s reports does work correctly when its definition of “Duplicate” is understood. It does not mean duplicate endnote sentences. It means duplicate citations in RM8’s internal database structure. This in turn means that you have to use Paste/Reuse for citations rather than Paste/Copy nearly all the time and that you have to merge your duplicate citations any time you import from RM7 into RM8. Otherwise, the Reuse Duplicate Endnotes option will not work and you will have humongously long endnote lists in your reports.