The same download can live in a media folder, an old downloads directory and a campaign area. Compare the files first. Matching filenames do not prove matching content.
Record the file and its version
Fictional example: two links are called “Delivery-terms.pdf”. One file contains the previous terms and the other the current version. Merging them by filename would overlook a meaningful difference.
Download public files and compare their version labels, page counts and, when useful, checksums. Identical checksums show identical file bytes. Different metadata can produce different checksums even when the visible PDF content matches.
Decide whether the site needs one preferred copy or deliberately separate versions. Historical documents should not accidentally be replaced with current ones.
If identical downloads must remain accessible, an HTTP Link header with rel="canonical" can identify the preferred URL. A canonical element on the page linking to the PDF does not set a canonical for the file itself.
Inspect the download’s response headers. If an old address has been fully replaced, a suitable redirect is another option. Update internal links to the chosen main URL and verify that it serves the document. Consolidation should not leave a download link pointing only to a generic homepage.
Related check: Check a canonical redirect destination.
If file delivery and response-header ownership are unclear, the Technology and stack review assesses the technical structure. It does not determine document validity.