Duplicate content
The same content reachable at more than one URL, such as HTTP and HTTPS copies or a category page's sorted and filtered versions.
Google lists several ways a site ends up with duplicate content (Google Search Central): regional versions such as separate US and UK URLs in the same language, mobile and desktop versions of a page, HTTP and HTTPS versions of a site, the sorting and filtering results of a category page, and a demo copy of the site left open to crawlers by accident.
Google says “Some duplicate content on a site is normal and it’s not a violation of Google’s spam policies.” It does warn that the same content at many URLs can confuse visitors, who may wonder which page is the right one, and can make it harder to track how your content performs in search results.
What Google does with it
When Google finds pages that look the same, it groups them and picks one as the canonical. It crawls that page most regularly and crawls the duplicates less often. It uses the canonical as the main source to judge content and quality, and a search result usually points to it, though a phone user will probably see the mobile page even when the desktop page is the canonical.
What you can do
You can tell Google which URL you prefer through HTTPS, redirects, your sitemap and rel="canonical" link annotations. Google calls that preference “a hint, not a rule”, so it may still pick a different page. For regional versions in the same language, Google says to use both canonicalization and hreflang. Before you pay for a tool to manage canonical tags, check what your store platform already sets.
Related terms
Tools for it
Sources
Updated Oct 14, 2026.