Duplicate language code in hreflang set — the fix
The hreflang annotations contain duplicate entries for the same language-region code, pointing to different URLs. Google cannot determine which URL is the correct one for that language.
Where this fits: indexability in SEO
Indexability is whether a crawled page is allowed into the search index at all. A page can be perfectly reachable and still tell Google to ignore it — through a noindex directive, a conflicting canonical, or an X-Robots-Tag header set by the server. These directives are absolute: one stray meta tag removes a page from search entirely. Indexability issues are the most binary in SEO — the page either can rank or it cannot — which is why they sit at the top of every serious audit.
Why duplicate language code in hreflang set hurts your rankings
Duplicate language codes create conflicting signals that may cause Google to ignore the entire hreflang set or pick an unintended URL for that language. This results in unpredictable behavior in international search results and potential traffic loss in affected regions.
This is a medium-severity issue: individually modest, but it compounds — dozens of medium issues across hundreds of pages add up to a real quality deficit in how search engines assess the site.
How to fix it
Remove duplicate hreflang entries so that each language-region code appears only once. If you have multiple pages for the same language but different content, they should have different URLs and separate hreflang sets.
Indexability best practices
- Audit noindex directives after every deploy — one templating mistake can deindex a section overnight.
- Give every indexable page exactly one self-referencing canonical URL.
- Never mix signals: a page should not be canonicalised away AND noindexed AND in the sitemap.
- Use hreflang pairs that reciprocate; a one-way hreflang is ignored.
- Check the HTTP layer too — X-Robots-Tag headers override what you see in the HTML.
The full library: SEO best practices, by category.
Frequently asked questions
What does "Duplicate language code in hreflang set" mean?
The hreflang annotations contain duplicate entries for the same language-region code, pointing to different URLs. Google cannot determine which URL is the correct one for that language.
Why does duplicate language code in hreflang set matter for SEO?
Duplicate language codes create conflicting signals that may cause Google to ignore the entire hreflang set or pick an unintended URL for that language. This results in unpredictable behavior in international search results and potential traffic loss in affected regions.
How do I fix duplicate language code in hreflang set?
Remove duplicate hreflang entries so that each language-region code appears only once. If you have multiple pages for the same language but different content, they should have different URLs and separate hreflang sets.
How serious is this issue?
This is a medium-severity issue: individually modest, but it compounds — dozens of medium issues across hundreds of pages add up to a real quality deficit in how search engines assess the site. It belongs to the indexability family of checks.
How do I find every page affected by this on my site?
Run a free Dr Urls audit: it crawls your site, detects duplicate language code in hreflang set on every affected page, shows example URLs, and generates a ready-to-use fix task. Re-scan after fixing to verify the issue is gone.
Does your site have this issue?
A free Dr Urls audit crawls your site, finds every page affected by duplicate language code in hreflang set, and hands you a ready-made fix task.
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