This is a myth that I hear a lot. The idea being that if you have
content on your website that is duplicated elsewhere on the web,
Google will penalize you for it.
The key to understanding what is really going on here is knowing
the difference between an algorithmic suppression and a manual
action.
A manual action, the situation that can result in webpages being
removed from Google’s index, will be actioned by a human at
Google.
The website owner will be notified through Google Search Console.
An algorithmic suppression occurs when your page cannot rank
well due to it being caught by a filter from an algorithm.
Chuck Price does a great job of explaining the difference between
the two in this article that lays out all of the different manual actions
available from Google.
Essentially, having copy that is taken from another webpage might
mean you can’t outrank that other page.
The search engines may determine the original host of the copy is
more relevant to the search query than yours.
- Duplicate Content Penalty
HOW TO SPOT SEO MYTHS: 20 COMMON SEO MYTHS, DEBUNKED