In a Google webmaster hangout, John Mueller He said that Google sometimes ranks websites that copy content from other sites.
Google generally doesn't rank duplicate content
Generally, Google only displays one version of the content (usually the original page):
“What would happen if we met exactly the same content elsewhere, then we try to make a decision about which of these is the canonical version, and we will choose one for indexing.”
Sometimes Google does it
Google will position the page with the copied content If you think it makes sense:
“On the other hand, if you have a product description on your website, and someone has copied the description and put it on eBay, then those pages, when you look at them overall, are going to be very different.
And this is not going to be the case where we're going to say, oh, some of this content is the same as some other site. Maybe we should take them equally. It's more a matter of looking at these pages and saying, well, these are two unique pages, let's put them in a separate index. However, Depending on what people are looking for, it might make sense to display one or the other.
If we recognize that someone is looking for something more eBay-oriented, then maybe we'll show the eBay version. If someone is looking for something that maybe they can pick up at a physical store nearby, then maybe we'll show the other version.
So from that point of view, it's not like they're hijacking your search results, or that there isn't some kind of problem going on. It's just a matter of our search algorithms trying to figure out which of these pages is the most relevant in every situation when someone is searching.
