If your site has spam penalties, perhaps due to something like dodgy link practices, it may easily rank lower than a scraper site, even if you have lots of original content.
The scraper sites with your content linking above your site may be there because of unrelated spam penalties on your site and may not be the cause of your lower ranking.
The scrapers may be both a cause and an effect, or they may be an effect but not a cause, or some variation in between.
Most of the time, if your site is older and has decent page rank, in my experience the scrapers are an effect but not a cause. Usually the duplicate penalties come in when nonscraper, decent ranking sites copy your entire content and your original content gets flagged as the duplicate (which I think happens more then the Google engineers may realize).