There is a Content Analysys section in Google Webmaster Tools, there you can see the Duplicate meta descriptions, duplicate title tags and so on...
i must agree with the others copyscape is the dogs vegetables but one of the things i never really thought about when it came to duplicate content was the meta tags and title tags i used. Quite often i never changed these if the pages were basically different content but the same subject, but an MSN moderator...yes they do exist... informed me that I should change these also. so always make sure very page has a different itle, description and juggle the keywords if you want to use the same ones.
i think u should use a webtracking tool like stat counter, visit their site, register. and you will be able to track and analyze the total traffic of your site. then if anybody even copies your content you will be able to see the total details of it, even the drive where he stores it. it's really good. i use it. http://www.statcounter.com
Besides using copyscape, hire a good writer. There are lots of web content providers claiming that they can write original articles when in fact all they do is copy-paste and rewrite articles from the web.