How to avoid importing duplicate copies of Kindle books when adding books to calibre

[kgwdc]

I'm coming back to my calibre library after a nearly two year hiatus. When I left off back in late 2016/early 2017, my Kindle for PC and calibre libraries matched, at roughly 6250 books.

I've since purchased another 900+ books from Amazon which have not yet been imported into calibre. Between the time that's passed and upgrades to calibre, I cannot recall the correct steps to bringing those new titles in without inadvertently re-importing the whole Kindle for PC library and creating thousands of unnecessary dupes that I'd then have to delete by hand.

Just now, I attempted to update calibre using Add books > Add books from a single directories, including sub-directories (Multiple books per directory), but I aborted that after 16 or 17 books were downloaded because I recognized titles coming through that were already in calibre.

Could someone please refresh me on (or point me to an existing thread that outlines) what the correct procedure is when you only want to bring in titles into calibre that were purchased after a certain date and have not yet been downloaded? I feel like it's something simple but I've searched and browsed around the forum and online generally and have yet to find anything.

Many thanks.

[BetterRed]

@kgwdc - I import 'new' books into an Intake library, then after rectifying any anomalies in author name and title values I use the Find Duplicates (plugin)->Library Duplicates tool to identify duplicates in the <Target> library. I then move the non-duplicate books to the =<Target> library using Copy to Library. I then work out what I want to do with the duplicates - discard, replace, merge etc.

I 'borrowed' the Intake library approach from a couple of MR members when I was doing my initial library load of ~30,000 books where I had quite a lot of duplicates. It worked well in that situation, so I've stuck with it.

But now I'm typically adding far fewer books - couple of dozen at most. And the number of duplicates is very low. I wouldn't add all 900 books to my Intake library, I do it in batches of 50 or 100 books - but that's a personal work pattern choice.

Added: also see Post #6 in Syncing Calibre from Baen

BR