On my site I offer PDF versions of all my articles. And google just indexed the PDF's. I wonder if i will be hit by dup content? Should I remove PDF's?
I don't think that's necessary. At worst, Google will index only one of the HTML version and the PDF version.
That's why I said, "at worst". I'm not sure Google treats PDF files the same as web pages, since it's not uncommon for people to offer formatted downloadable PDF versions of articles.