Internal or external
Internal duplicate content usually comes from technical causes: URL parameters, http and https versions, print pages, color variants of one product, city pages with cloned copy. External duplicate content lives on other domains: an article republished by a partner, text scraped by a third-party site, or a manufacturer's description reused word for word by dozens of online stores.
What Google actually does
Google clusters similar pages and picks one as canonical, normally the only version shown. There is no penalty for technical duplicates: the risk is that Google picks a variant you did not choose and that links split across several URLs. Things change when duplication becomes a strategy: Google's spam policies target content scraped from other sites without added value and pages mass-produced to manipulate rankings, both of which can lead to a manual action.
The most common cases on small business sites
- Product pages using the manufacturer's description verbatim.
- "Service + city" pages where only the town name changes.
- A site reachable with and without www, over http and https.
- A blog post republished unchanged on Medium or LinkedIn.
- Tag and category archives listing the same posts.
Fixing each case
For technical variants, a 301 redirect or a canonical tag pointing to the main URL is enough. For low-value pages such as tag archives, a noindex tag keeps them from competing with real pages. For manufacturer copy, rewrite your best sellers first with information only you have: usage tips, your own photos, customer feedback, comparisons with similar models. When a partner republishes your article, ask for a canonical pointing back to the original. Then check the Page indexing report in Search Console: the status "Duplicate, Google chose different canonical than user" shows which pairs still need work.