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The two affiliate sites are well etablished and huge sites, so I guess they know what they are doing... Lots of affiliates are really smart people.  They often have websites that are much more powerful than the vendors that they sell for.  The result of that is that their sites will often displace the program site in Google search results - because they are more powerful. Lots of people say that people who copy your content will not outrank you, but those folks need to upgrade their knowledge.  If your content is published on more powerful sites or lots of less powerful sites you can be outranked or filtered from the SERPs. If you tell these folks to take down what is currently published on their website or point rel=canonical to your site you run the risk of them refusing or taking your product off of their page and replacing it with your competitors product. The best way to fix this is to look towards the future and have rules for all new affiliates that they must not republish content from your website.   That will reduce the number of affiliates that you acquire and you run the risk of them writing really bad content that misrepresents your product. Affiliates can be your strongest ally or your strongest competitor.  Tread carefully.