Duplicate Content

Why It Matters

Duplicate content causes search engines to make arbitrary indexation choices that may favor competitor copies over your original content. Beyond ranking confusion, it wastes crawl budget and dilutes link equity across duplicate versions. For AI visibility, duplicate content reduces citation probability because AI systems prefer citing the original, authoritative source and may not correctly identify which version is original.

How It Works

Search engines identify duplicate content using content fingerprinting and similarity scoring. When duplicates are found, the canonical signal (explicit canonical tags, redirect patterns, link equity concentration) determines which version is selected for indexation. Without canonical signals, search engines make their own selection-which may not favor your preferred version.

Use Cases

• E-commerce sites with identical product descriptions copied from manufacturer specifications
• News syndication creating exact copies of articles across multiple publisher domains
• CMS-generated HTTP and HTTPS versions of the same page lacking canonical tags
• WWW and non-WWW domain variants both accessible without consistent redirect
• Pagination creating near-duplicate content across page 1 and subsequent pages

Best Practices

• Implement self-referencing canonical tags on every page to declare the preferred indexed version
• Consolidate site variants (HTTP/HTTPS, WWW/non-WWW) with 301 redirects to a single canonical domain
• Write original product descriptions rather than copying manufacturer content
• Use hreflang tags rather than content duplication for international language variants
• For syndicated content, implement canonical tags pointing to the original source domain
• Use Google Search Console URL Inspection to verify which version Google has indexed for key pages