Two files have the same name, size, and thumbnail. That still does not establish that one should be deleted. One might be an intentional backup; another might be required by a linked project. Duplicate cleanup therefore has two stages: checking whether the contents match and deciding which locations still serve a purpose.
Limit the search area
Start with one personal collection or completed project. System folders, application directories, active photo libraries, and backup sets should not be included in an indiscriminate cleanup. Repeated files may be intentional there. Searching every drive and accepting all suggested deletions is a poor first experiment.
Make a verified backup before substantial changes. Also decide which location should remain authoritative. Without that decision, an automatic selection can remove files from the very places where applications or colleagues expect to find them.
Names are clues, not proof
A duplicate finder may group files by size and then compare their contents. A cryptographic hash such as SHA-256 provides a useful content fingerprint. Microsoft's Get-FileHash is one tool for this kind of check. Renaming an otherwise unchanged document does not change its content hash, so a different name alone does not make a file unique.
Different hashes do not necessarily mean that two photos look different. Metadata edits, compression, or a small adjustment change the file. Visual similarity tools therefore still need human review. For records and documents, a tiny difference such as a corrected date can be significant.
Choose the surviving location deliberately
Check the full path, file type, revision, and use. A file inside a backup is not an unnecessary working copy. An identical logo may also be required in several independent delivery packages. Do not remove such components simply because their bytes exist somewhere else.
Where appropriate, move selected candidates into a clearly labeled review area inside the controlled collection first. Then test the affected documents and projects. Remember that moving or deleting items in a synchronized folder can propagate to other devices. A local cleanup action may not stay local.
Keep a record of the decision
A short record of removed paths, surviving paths, and the date helps answer later questions. A plain note is enough for a small collection. After a few normal work sessions, check again that expected files remain available before permanently emptying the review area.
The main benefit is often clarity about the current version rather than reclaimed storage. If nobody knows which file to use after cleanup, the collection still lacks a working rule. Improve that rule instead of repeatedly running a duplicate finder over the same unresolved arrangement.