Duplicate content can often arise without our knowledge, despite our best efforts to prevent it.
so how can i quick checks for this one...pls share ur ideas...

You can check the content whether it is duplicate or not by following sites copyscape.com or small seo tools.

Duplicate content is content that appears on the Internet in more than one place (URL). When there are multiple pieces of identical content on the Internet, it is difficult for search engines to decide which version is more relevant to a given search query. To provide the best search experience, search engines will rarely show multiple duplicate pieces of content and thus, are forced to choose which version is most likely to be the original—or best.

Duplicate content is not good for SEO use original content for website.