Most people nowadays have a misunderstanding of what the problems really are with duplicate content. Unique content is usually very beneficial for your websites and articles, but isn't always an absolute requirement.
Google doesn't really care about duplicate content unless you're building a bunch of duplicate landing pages on a single website. That's where the idea of a duplicate content penalty comes from and it's similar to keyword stuffing.
The only real problem regarding duplicate content among different websites is that it creates more competition in the index for the same content. The first instance found will have a slight advantage, but that advantage can quickly disappear when other sites do a better job optimizing for other factors.
Article writers have to worry about duplicate content for a different reason. Most article directories will only accept original content. Programs like copyscape were created to identify duplicate content for people doing directory submissions.
Somehow over time the idea of a duplicate content penalty for having duplicate landing pages, and the idea of needing to have unique content for article directories merged into a single idea that duplicate content is bad and there is a duplicate content penalty for any kind of scraped content. If that were really the case then it would be virtually impossible for content aggregators and auto blogs to rank well in the serps. In fact it would be almost impossible to get an ecommerce site to rank well if the product is sourced from a wholesaler since the bulk of your stores content is the same as every other online retailer for the same products.
There's a couple other threads right now discussing this topic in even more depth. If you want to understand more about duplicate content, when it's ok to use it, and when it's best to be unique then you should read these threads as well.
