Disadvantages of Duplicate content backlink?

Hello guys,
What is the disadvantage of a backlink from duplicate content?

Actually, low quality backlinks is full of disadvantages. But If you doing right backlinks that you will get advantage from Search Engine.

If same content appears at more than one place, then it will be considered duplicate content. These “places” refer to two different URLs. This means that if your content appears on two unique web addresses, then it will be categorized as duplicate content. Now, it is difficult to decide who copied the content and whose content is original and unique. This duplicate content can both invite penalties and difficult in ranking on search engines. Even if the search engine doesn’t penalise the duplicate content, it will be hard for the search engine to decide which content is more relevant to a particular query.