Duplicate Content

Duplicate content is identical or near-identical content living on more than one URL, either inside a single website or across domains. Google prefers to show one result per piece of content and filters the copies out, so only one version gets a place in the search results.

The penalty myth

Duplicate content does not normally trigger a penalty. The real problem sits elsewhere: Google decides for itself which version ranks, and it is rarely the one you would have pointed to. Internal duplicates also spread link value and crawl resources across several URLs, so none of them stands strong in SEO. Only deliberate copying at scale draws a hard response from Google's spam systems.

Where duplicates come from

Almost nobody copies on purpose. The classic sources are URL parameters and filters generating endless variants of the same page, a site reachable over both http and https, print versions, and manufacturer product descriptions used word for word by hundreds of other shops.

How Google consolidates

Google merges duplicates itself when the signals are clear. A canonical tag names the original, and a 301 redirect gathers moved and retired pages on the URL that stays. Canonical is a hint rather than an order: Google can settle on a different canonical version if internal links and sitemaps point somewhere else. The guide to site health and redirects works through the cleanup.