Match strength
How alike two photos must be before Deduplo calls them the same.
The strength slider runs from 70 to 100.
| Setting | What matches | Use it when |
|---|---|---|
| 100 | Identical copies only | You want exact duplicates and nothing else |
| 90 | Resized, re-saved, lightly edited copies | Almost always — this is the default |
| 85 | Heavier edits, stronger crops | You know the library holds edited versions |
| 70–80 | Anything that looks alike | Rarely — check every set by hand |
Lower is not better
As the bar drops, Deduplo starts joining photos that merely resemble each other — three different pictures of the same beach, or two portraits with a similar background. Below about 80, sets stop being "copies of one photo" and become "photos that look a bit alike".
Scans get dramatically slower. Deduplo shows a hint under the slider when you cross that line. Unless you have a specific reason, keep the strength at 88 or above.
Changing it does not mean re-scanning
Move the slider after a scan and Deduplo regroups what it already knows — no files are read again. That makes it cheap to try 95, look at the results, and drop back to 90.
The match filter
Separately from the slider, the Match badge above the results hides sets below a match percentage you choose. The slider decides what Deduplo finds; the filter decides what you are shown right now.
Why did these match?
Right-click any set and choose Why did these match…. Deduplo explains in plain words what made it group those files. If the answer does not convince you, use Not duplicates — never match again and that pair will be left alone in every future scan.