--- title: "You decide which side is allowed to lose files · DuplicateDuster" description: "Sources hold what you keep, targets are what gets cleaned, and only the target side ever gets a checkbox. Then one real scan, start to finish." url: "https://royalsoftworks.com/products/duplicate-duster/two-sides/" source: "https://royalsoftworks.com" format: "markdown" note: "Markdown rendering of the HTML page at `url`. Same content, same canonical URL." --- DuplicateDuster · 1 of 2 # You decide which side is allowed to lose files. Sources hold what you keep, targets are what gets cleaned, and only the target side ever gets a checkbox. Then one real scan, start to finish. The safety model ## You decide which side is allowed to lose files. Most dedupe tools hand you a pile of matches and leave you to work out which copy was the real one. DuplicateDuster asks first. The source folders hold what you're keeping; the target folders are the ones being cleaned. Matches are only ever paired across the two, and only the target side gets a checkbox. Source · keep ### The library you trust Your photo library, the canonical project archive, the NAS share everything else was copied from. Nothing here is ever selectable, and nothing here is ever removed — it is shown alongside each match purely for context, badged _keep_. D:\\Photos\\2024\\ \\\\nas\\archive\\projects\\ Target · clean ### The mess you're clearing The old laptop's Desktop folder, three generations of manual backup, the downloads directory nobody has opened since 2022. Only these files can be selected, and only these files can be removed. E:\\old-laptop\\Desktop\\ E:\\backup-2019\\ · E:\\backup-2021\\ #### Folder matches, not just files When a target folder holds exactly the same files, under the same names, as a folder in the source, the folder itself is reported as a match — and only the topmost one, so \`photos/\` doesn't bury you in its own subfolders. #### System paths refused outright Windows, Program Files, /usr, /etc and their equivalents are skipped during the scan and refused again at delete time, whatever is selected. #### Empty folders cleaned up after Directories left empty by a cleanup are removed, deepest first — but only if they are genuinely empty. Anything still holding a file you kept stays. Inside the app ## One real scan, start to finish. Both frames are the program running on an ordinary Windows machine, not a render. The filenames in the results are blacked out because it is a real disk; every number beside them is untouched. A finished scan What happens to a copy ![DuplicateDuster having scanned 84,331 files and found 588 groups of duplicates totalling 21.7 GB that can be reclaimed](https://royalsoftworks.com/shots/duplicate-duster/results.png) One real scan: 84,331 files compared, 588 groups of genuine duplicates, 21.7 GB reclaimable. The top row alone is five copies of the same 208 MB file. Names are blacked out because it is somebody's actual disk, and the version in the corner was corrected to 1.3.0 — the capture came off a development build, which reports the wrong one. [Previous DuplicateDuster overview](https://royalsoftworks.com/products/duplicate-duster/) [Next Free and Pro](https://royalsoftworks.com/products/duplicate-duster/editions/)