If you are using duplicate content then it is advisable to do not use duplicate content, as Google has changed algorithm and giving more emphasis on duplicate content
i know this stuff , but its very difficult since i worked my way to the top of rankings and then tried to stay there but google penalized me , i am still working , but cannot seem to see any improvements ,will surely update you soon , but google is surely trying hard to get unique content and it surely expects it from those who are ranking high
This will happen more in the future. Google is now very strict about content. One article on many website will not take effect. Write up fresh and new content. Demands more hard work.