Setting up a duplicates scan

Pick folders, press Find Duplicates, and the defaults are already sensible. This page is for when they are not — how to carve folders back out of what you picked, and every control in Scan parameters, what it defaults to, and what you give up by changing it.

Excluded folders

Under Selected folders, on the setup screen itself, is a second list: Excluded folders. It carves specific folders out of the ones you picked, and what it carves out is never opened, never hashed, never counted.

While it is empty it reads Nothing is excluded — all of each selected folder is scanned, with an Exclude a folder… button beside it. Once there is one, the line is replaced by a strip of tiles — struck-through name, parent folder underneath, so Archive and Archive are told apart — and a + tile to add the next.

An exclusion has to sit inside something you selected, and DuoBolt says so at the moment you pick rather than silently keeping a rule that can never fire:

• Picking a folder you selected as a scan root is refused — excluding it would cancel it out and leave nothing to scan there. Remove it from Selected folders instead, or exclude a subfolder of it.
• Picking a folder outside every selected root is refused too, because it would not change what gets scanned. Add the folder that contains it first.

Exclusions live with the scan you set up: Duplicates and Similars keep their own lists, and both are saved into the setup that Scan History replays.

Excluded, skipped, or protected?

Three different things, and the difference is what happens to the files:

• Excluded folders — this section. Specific folders, chosen by hand, that the scan never enters.
• Skip folders — rules rather than a list: by name, by folder extension, or the built-in NAS and Library sets. One rule prunes every folder that matches it, anywhere in the scan.
• Protected folders — the opposite end. Those folders are scanned and their files appear in the results; what they can never be is selected for removal.

Exclude a folder when its contents are noise. Protect it when its contents matter and you want to see them without any risk of losing them.

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The info card

Before you scan, the card under the folder list summarizes the setup in chips: the size range, what is being skipped, and — importantly — only the settings that deviate from the defaults. If it says nothing about symlinks, symlinks are at their default.

The status line reads Ready to scan 3 folders, or No folders selected.

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Scan parameters

File size range

Two handles over a fixed ladder, from 1 KiB to Unlimited. It defaults to 64 KiB and up.

That default is the one worth knowing about: everything smaller — small text files, config files, and every zero-byte file — is outside the scan entirely. Drag the lower handle to 1 KiB if that is what you want to find.

An upper bound is occasionally useful in the other direction: cap it to exclude the video files you already know about and let the scan finish sooner.

File extension filter

A dropdown — Include or Exclude — and a token field: Type extensions (e.g. jpg, mp3, pdf). The two are exclusive; choosing one clears the other.

Include is the strongest speed lever DuoBolt has. A scan restricted to jpg, heic, raf never even stats the rest of the disk.

Caution

With an include list set, files with no extension at all are skipped. It is a whitelist in the strict sense.

Ignore

Toggle	What it skips	Default
System files	.DS_Store, Thumbs.db, desktop.ini, etc.	On
Hidden files	Files starting with . or flagged hidden	On
Hidden folders	.git, .svn, .cache, etc.	On

Turning these off is how you get the widest possible scan — and a lot of noise you almost certainly do not want to clean.

Skip folders

Library containers (on) — skips ~/Library/Containers and ~/Library/Group Containers.

NAS & system folders (on) — skips the snapshot, recycle and thumbnail folders that Synology, QNAP and TrueNAS keep inside shares. The reason is worth repeating in full: snapshot copies are identical to your files, so scanning them invents duplicates.

Names — a token field, e.g. node_modules, .git.

Extensions — a token field, e.g. app, bundle. This is the one that handles packages and bundles: a folder whose extension matches is pruned along with everything inside it. On macOS, app, photoslibrary, aplibrary and imovielibrary are the usual suspects — they look like single files in Finder but are large directory trees full of internal near-copies.

Everything here is a rule, matched against every folder in the scan. To keep one particular folder out — this Backups, not every folder named Backups — use Excluded folders on the setup screen instead.

Symlinks

Follow symlinks (off) — may increase scan time and duplicate count.

Collapse symlinks (on) — treat symlinks as originals in duplicate detection. With it on, a file reached by several links is admitted once. This is also what keeps hardlinks from appearing as duplicates of themselves; see the honest limits.

Performance

Two-stage scan (on) — faster duplicate detection by hashing files in two passes. It changes speed only, never results.

Detect APFS clones (on, macOS) — avoid counting files that share storage on APFS as recoverable duplicates. Explained in full under APFS clones.

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Resetting

Reset to defaults appears in the dialog footer only when something is actually non-default, and each individual slider carries its own reset button for the same reason. If a control shows no reset, it has not been touched.

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Running it again

You do not have to rebuild a setup you have used before. Scan History keeps every scan with its full configuration — folders, size range, extensions, options — and Run again repeats it exactly. See history and restore.

Next

Reading the results — filters, sorts, bulk rules, and the two numbers in the footer.

On a NAS

DuoBolt for NAS — mounts, caching, and what to exclude on a share.