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Hi Jason I wouldnt think the duplicate content is the issue, especially assuming the main keyphrase you are after had the homepage ranking for it (which doesnt have the dup issue) right? Moz is not showing you anywhere near as many links to the domain as ahrefs is, I would look at GWT also and have a good look through all your backlinks, at first glance there seems to be a chunk of obvious spam/seo type links in your profile that might be a more likely cause of the trouble. If you are not getting any more of those and have a marketing plan in place then it might just be a matter of keep doing what you are doing and you will start ranking again. But you will want to make sure you know where those dodgy links came from and that you are not going to be getting many more.