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Duplicate Content: What It Is and How It Hurts Your SEO

Duplicate content is a common SEO mistake that can seriously harm your Google rankings. Find out what it is, how to find it, and how to fix it.

5 min read7 April 2026
duplicate contentseo duplicate contentcanonical tagscontent penalties

Duplicate Content: What It Is and How It Hurts Your SEO

Duplicate content is exactly what it sounds like: the same (or very similar) content appearing at multiple URLs on your website — or appearing on your site that also appears elsewhere on the web.

It's one of the most commonly misunderstood SEO issues — and it can silently drain your rankings.

Why Google Dislikes Duplicate Content

When Google finds the same content at multiple URLs, it has to decide which version to show in search results. This 'dilutes' the ranking potential between multiple URLs, rather than concentrating it on one.

Google may:

  • Choose the 'wrong' version to index
  • Show neither version if it can't decide
  • Assign less authority to both pages

Common Causes of Duplicate Content

1. HTTP vs HTTPS

If your site is accessible at both http://example.com and https://example.com, Google sees these as two different URLs with identical content.

Fix: Redirect all HTTP traffic to HTTPS.

2. WWW vs Non-WWW

Similarly, www.example.com and example.com can cause duplication.

Fix: Choose one version and redirect the other to it.

3. Trailing Slashes

/page and /page/ are different URLs but identical content.

Fix: Standardise your URL format and add canonical tags.

4. Session IDs in URLs

Some e-commerce platforms add session IDs to URLs, creating thousands of duplicate pages.

Fix: Configure your CMS to avoid session IDs in URLs or use canonical tags.

5. Printer-Friendly Pages

Old-fashioned printer-friendly versions of pages create exact duplicates.

Fix: Remove them or use canonical tags pointing to the main version.

6. Copied or Syndicated Content

Copying content from other websites — or having your content republished elsewhere without a canonical tag — creates cross-domain duplication.

Fix: Always create original content. If syndicating, ensure the publisher adds a canonical tag pointing to your original.

7. Similar Category/Tag Pages (WordPress)

WordPress generates multiple index pages for categories, tags, and archives — often with very similar content.

Fix: Use a plugin like Yoast SEO to noindex low-value archive pages.

How to Find Duplicate Content on Your Site

Free tools:

  • Google Search Console (Coverage report)
  • Screaming Frog (free up to 500 URLs)
  • Siteliner (free duplicate content finder)

Search trick: Type site:yourdomain.com 'exact phrase from your content' — if multiple results appear, you may have duplication.

The Fix: Canonical Tags

A canonical tag tells Google which version of a page is the 'master' version. Add to the <head> of each duplicate:

<link rel="canonical" href="https://www.example.com/main-page/" />

Need a Duplicate Content Audit?

Our SEO service includes a full technical audit that identifies and fixes duplicate content issues. Get in touch.

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