Hi,
My name is Ricardo and I think that I can help you with your project.
I will use search, attention to locate content that is duplicated. I'm thinking to do some crawling on the websites to locate that content, but I need to see how the content is expose to have an idea of how to automated that content for duplicated search. But in one day, I think is good to do with manual testing, but it's strongly recommended to automated that test. Because I can search manually on the websites for duplicated content, but if someone added after my test duplicated content, we will need to do all those that manually again to check.
Sorry for the big text.
Regards.,
Ricardo França