On import lightroom 5.3 still does not recognize previous imports of the same file name. I have the "do not import suspected" checked, but LR5 does not exclude the old files. I have had this question in Forum last month, but nothing has helped. Import has Copy, New Photos and Do not import suspected duplicates checked. No problem with LR4.4 on imports
I think this is a bug, although I thought it was there in Lr4.4 too (catalog dependent).
If I remember correctly, one of the things that can cause this problem is importing from catalog - doesn't update a critical field or something like that - don't quote me..
several months ago I placed a larger drive in my system. I first used explorer to move the files to the new drive(named 2013) with copy and paste, but I noticed several hundred images were missing when I then linked the images. So then I moved them with lightroom instead (named 2013x). To be sure I had all the image files I went to import the 2013 into the 2013x thinking that Lightroom 5.3 would see the duplicates and ignore these, that way I could see any missing images were found. On import I chose "ignore duplicates" move and new photos checked. Lightroom instead copied the old files and changed the filename by adding a -2 or -3 right along side the original files. I found that on a import of a old card the same thing will happen, older images that were imported were ignored and added with the file name change. I did this on a small scale of a few hundred images. Suggestions? I have been able to delete the extra files because in the
keywords I added a word I could locate any -2 or -3 in attributes. Any reason why LR can recognize previously used files names on import. I can view original files in LR, have optimized several times. Suggestions?
It could be that Geoff was suggesting you try removing the preference file to see if it helps.
I don't think it will help, since I recall other cases when this problem was not improved by removing preference file - still, may be worth a shot.
I think it's a catalog thing (if my aging memory serves me correctly), so you could try exporting everything as catalog (and then open exported catalog) and see if it's any better - the problem might get "exported" too, but that's all I got (alternatively, you could create a new catalog, and import everything from your current catalog - again, the problem might get "imported" too, but may be worth a shot).
Of course, backup your original catalog before making "experimental" changes, and beware: publish service stuff isn't exported/imported.
PS - if it is a catalog thing, you may be able to glean something from inspection via sql client app, or dump as text file and search... - advanced users only......