I thinks it does. I just found out a few webistes ripped most of my sites content. Then slowly seeing my site droping in serp rankings.
Duplicate content will cause one of the duplicated documents to be seen as original and the rest won't be listed. One of the key things to prevent this is to use unique Title tags and Description tags. Even if everything else is unique the search engines will tag it as duplicate content if those are duplicated. One thing you can do to combat site scrapers from duplicating your content, is make sure you put links in your content to your site with absolute URL's. (http://www.yourdomain.com/linked-page.html vs. /linked-page.html). That way you will have some free links to your site if people rip your content. It also tends to help Search Engines sort out who the originator is. If they are scraping your content you should file a DMCA report with Google and others , and they can remove the ripper from the rankings. Google's DMCA report can be found here: http://www.google.com/dmca.html
Definitely 'coz SE detect duplicate contents... It will be on supplemental results page...Your site will never appear on Search Engine Rankings....
Dup content is your number one exit from SERPs. SEs think dup content diminishes the value of search results as visitors think they are not getting quality content.