Backups, imports and exports have left you with duplicate photos, and the copies do not carry the same metadata: one has the keywords, another the caption. You want to find the duplicates and combine their metadata, so that whichever copy you keep has everything.
Do it in Parergon
- 01
Find the duplicates
Choose Tools ▸ Intelligence ▸ Find Duplicates… and pick Exact to find identical copies, in this folder, its subfolders or all your Libraries. Exact matching is free. Similar finds near-duplicates, such as resized or re-saved copies, and is part of Parergon Pro.
- 02
Merge their metadata
Each group shows its copies and how similar they are. Choose Merge Metadata… on a group: every copy gets the group’s full set of keywords, and empty fields such as title, description, creator, copyright and the city or country names are filled from the other copies (GPS coordinates are not). Fields that already have a value are never overwritten. Merging is part of Parergon Pro.
- 03
Then remove the extra copies yourself
Merging never deletes, moves or trashes anything. Once every copy carries the same metadata, use Reveal in Finder to remove the ones you do not need. Edit ▸ Undo reverses a merge in one step.
Merge Metadata combines keywords and fills empty descriptive, rights and location fields; it does not copy camera data or GPS coordinates. Duplicate finding covers photos, not videos.
Why this happens
Duplicates rarely stay identical. A copy exported from Lightroom carries its keywords, a copy from a phone backup carries the original date, a copy someone captioned for a client carries a description. Deleting the wrong one deletes that work.
Exact copies are found by comparing the files byte for byte. Near-duplicates, such as a resized web version, need image comparison, because their bytes differ even though they show the same picture.
Other ways to do it on a Mac
- Apple Photos
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For photos in your Photos library, the Duplicates album lists copies, and Merge keeps the best version while combining their data in the library. It does not cover photos in folders outside Photos.
- ExifTool (free, Terminal)
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This adds the keywords of one copy to the copy you keep, in both XMP and IPTC. Run it once per extra copy; keywords already present are added again, so check the result.
exiftool -tagsFromFile copy.jpg "-XMP-dc:Subject+<XMP-dc:Subject" "-IPTC:Keywords+<IPTC:Keywords" keep.jpg
Questions
Does merging delete my duplicates?
No. Merge Metadata only writes metadata; every copy stays where it is. Deleting the extras is up to you, after the merge.
What if two copies have different captions?
Both keep their own: merging only fills fields that are empty. To make one caption win everywhere, copy it with Tools ▸ Edit ▸ Copy Metadata… (Pro), which replaces the targets’ values with the source’s.
Can I combine keywords without finding duplicates first?
Yes. Add the files to the Compare Tray (Pro) and choose Equalize Keywords, which gives every file the combined set, or Copy Keywords to merge one file’s keywords into another.
Go deeper: Keyword and organize your whole library.