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I've discovered that one of the sites I am working on includes content which also appears on number of other sites. I need to understand exactly how much of the content is duplicated so I can replace it with unique copy. To do this I have tried using tools such as plagspotter.com and copyscape.com with mixed results, nothing so far is able to give me a reliable picture of exactly how much of my existing website content is duplicated on 3rd party sites. Any advice welcome!