Duplicate Content

When the same content is used on two or more pages, it's referred to as duplicate content. This includes content of the same website (e.g. on different subpages) as well as content from different websites (different domains).

Search engines can recognize duplicate content. And they're getting better at recognizing which is the original and which is the duplicate. While the original won't be affected by it, the duplicate can get a worse position in the SERPs. Search engines don't tell how exactly they decide which one is the original and which one is the duplicate.