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You mean MOZ.com considers it duplicate content, right? Duplicate content, as in having pages with duplicate content will cause you a "ding" in your rankings-- but mostly when it's duplicated from domain-to-domain. I have never seen evidence of duplicate content on the same website, harming a website, no matter what Google says about canonical links. (I still think you should use canonical links.) But assuming that having some duplicate content on your site is really very harmful... Google knows the difference between a page that is actually duplicate content and plain old blank pages. MOZ may consider blank pages duplicate, but MOZ isn't nearly as sophisticated as Google. I wouldn't sweat it myself.

You have two issues here. 1. Interlinking site sis never a good idea with a dofollow links, so I would look at that. But it is not an issue if its nofollow. 2. Googlebot only crawls from the US and will only every crawl the US site if you send all US ip's to the US site. I would use hreflang on your site. https://support.google.com/webmasters/answer/189077?hl=en Otherwise you will confuse Google and possibly get a cloaking issue on the site. Also look at the canonical tag https://support.google.com/webmasters/answer/139394 AND https://support.google.com/webmasters/answer/182192?hl=en&ref_topic=2370587