Duplicate content

Why duplicate content matters

When identical or very similar content exists at multiple URLs, search engines must choose which version to rank. This dilutes your ranking potential—instead of one strong page, you have several weak ones competing against each other.

Google rarely penalises duplicate content directly, but it does filter results to show only one version. If search engines choose the wrong version—one with fewer backlinks, poorer internal linking, or less user engagement—your best page remains invisible.

Common duplicate content causes

Technical variations create duplication: www vs non-www, HTTP vs HTTPS, trailing slash vs non-trailing. The same content appears at multiple addresses. URL parameters from tracking, sorting, or filtering multiply URLs exponentially.

E-commerce sites often have products accessible through multiple category paths. Printer-friendly versions, mobile-specific URLs (less common now with responsive design), and paginated content all create duplication without careful handling.

Fixing duplicate content

Canonical tags tell search engines which version to prioritise. Every duplicate should have a canonical pointing to the master version. This consolidates ranking signals without breaking existing links.

301 redirects work when you want to eliminate URLs entirely—redirecting HTTP to HTTPS, or www to non-www. Visitors and search engines all reach the same address. Use robots.txt to block crawling of low-value parameter variations.

Cross-domain duplicate content

Publishing identical content on multiple sites—your own or others—creates duplication. Search engines will rank one version, rarely both. If you syndicate content to other publications, request they add canonical tags pointing to your original.

Scraped or stolen content creates duplication you don't control. Google usually identifies the original source correctly, but filing DMCA takedowns protects your content when automated detection fails.

Prevention strategies

Plan clean URL structure before launch. Make decisions about www, HTTPS, trailing slashes, and implement them consistently. Configure automatic canonicals in your build process. We handle this in every Astro site to prevent duplication from day one.