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Hey Josh, You may want to speak with your developer on this one PHP is a server language and could be generating the unique pages and causing Roger to crawl twice depending on which way he approaches the page. I apologize for the delay here as I was not receiving notifications on this post.

Hi Josh! Thanks for reaching out! My name is Erin, and I'm on the Help Team here at Moz. It looks like you've been working with David and Michael on this, and I'm really glad to see that you've brought this question to our awesome community! While we're able to tell you how our site detects duplicate content, advising you on how to implement strategy on your site is a little out of our realm of expertise. I'd have to be a web dev or a consultant to point you in the right direction, and the truth is I was a history major. Sorry we don't have more resources for you on this one! It's my hope that someone here in the community has some insights for you. I'll leave this question as "unanswered" in hopes that someone has some advice. Good luck, and have a wonderful weekend! Erin

That code should automatically 301 redirect all urls with www in them to non www versions - you can check if this is working properly with this tool (for the moment I do not see the redirect working though). So for any duplicates you are seeing because of that specific issue this will fix them. You should then wait for the next moz crawl to happen and should see less duplicates (since these ones will be removed) - this will show you what duplicate issues are still apparent (as mentioned there are a number of reasons that duplicate content can occur) and then you can focus on what kind of duplicates they are and what fix(es) may be needed to address them. It is best to fix one thing at a time and not pile a whole bunch of changes you are not sure about on top of each other - it keeps it easier to bug track if something goes wrong!