We think it may have to do with unicode normalization differences. The umlaut-u in your image's title can be represented multiple ways in unicode.
Could you create a test catalog and only add that one image to it? First use Scan to Catalog (copy that image in the Finder to a new folder and scan that folder). Then you could Reveal in Context and select it and do a Catalog->Include in Catalog. See if that makes a duplicate. If you can get your test catalog to have a duplicate, could you then share it with us?
To solve the immediate problem, you could select the duplicates and remove them (Catalog->Remove from Catalog). I expect that the others will stay in the catalog.
-Kirk
Good detective work Kirk! I was able to easily get the photo to duplicate. I have the one photo catalog in Dropbox. I have sent you a PM with the link. As added info, based on your comment about the umlaut-u, I researched the others that were duplicating. All have special characters in the naming.
i.e. Città Metropolitana di Firenze, Málaga, Bréhémont, Évora
Further research showed that the duplicates are throughout the catalog anywhere special characters were used. I have not yet tested to see if the cause is the filename only, or other metadata. I use GPS locations in naming of the files, so the metadata is building the filenames.
Look forward to your findings.
Thanks,
Dennis
