When Search Console reports “Duplicate, Google chose different canonical than user”, it is telling you your signals conflict. The tag is only one vote.
Work through in order
- Are the two pages genuinely the same content? If so, Google choice may be perfectly sensible.
- Do internal links point at your preferred URL, consistently?
- Does the sitemap list the preferred URL and only that one?
- Do redirects agree with the canonical, or fight it?
- Is the preferred URL faster, HTTPS, and cleaner than the alternative?
When pages are similar but distinct
If two pages are genuinely different but Google treats them as duplicates, the answer is differentiation, not markup. Merge them or make them substantially different.
Alien Road recommends: when Google picks a different canonical than you declared, assume it noticed something real before assuming it is wrong. In roughly half the cases we investigate, the “wrong” canonical is the URL that actually receives the internal links and external references, the declaration was the outlier.