Today’s Question: I find that Lightroom Classic will import duplicates if their names differ even if they’re identical, like from a checksum perspective. Sounds like I’m doing something wrong. Thoughts?
Tim’s Quick Answer: When you enable the option to not import suspected duplicates in Lightroom Classic, the images are only evaluated based on the original filename (if available), the capture date and time from metadata, and the file size. In this example the issue is probably that the files were renamed without retaining the original filename in metadata.
More Detail: Lightroom Classic does not use a checksum to compare images being imported to determine if they are duplicates of any other images already in the catalog. A checksum is a value based on an algorithm to describe the contents of a file, which can provide a more accurate way of determining whether two files are identical. Instead of a checksum, Lightroom Classic uses the original filename, the capture time, and the file size.
In this case I suspect the issue is that the filename was changed without preserving the original filename in metadata. If you use Lightroom Classic or Adobe Bridge to rename files, the original filename will be retained in metadata. This original filename can be found in the Preserved Filename field in the File Properties section of the Metadata panel in Bridge, or in the Original Filename field on the Metadata panel if you select “EXIF and IPTC” from the popup to the left of the Metadata heading.
If you renamed with other software or through the operating system, the file can be renamed without preserving the original filename. In that case, Lightroom Classic will not identify files with different names to be duplicates even if they are, because the filenames don’t match and the original filename isn’t preserved in metadata.
But, as long as you don’t rename photos using software that doesn’t preserve the original filename and don’t change the capture time, true duplicates should be detected by Lightroom Classic upon import as long as you keep the “Don’t Import Suspected Duplicates” checkbox turned on.
