Are those articles also on other sites? If so then Google probably sees them as duplicate content and there's no reason for them to index the same content twice.
If it means anything I can find both pages of your site when I search for the title of the articles.
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I assume that other people are using the articles on their sites, however there is alot of 'other content' on my article pages. I cant see why it would be considered duplicate???
Outside of your basic site layout the page is likely exactly the same to any other site that downloaded that same article. Why would Google need to include that same article more than once in their index?
I can't tell you with 100% certainty what Google does and doesn't consider duplicate content, but keep in mind the word after duplicate is content and I would think they would be most focused on the content.
The search for which I found your pages was for the title of the article with quotes around it like this search: