A very common business owner mistake is to accidentally create duplicate content and be penalized by Google.
Many businesses write articles to help promote their business and think that sending that article out and trying to get it published is a good thing. They also put these same article(s) on their web site and do not realize this is against Google Guidelines. It is not easy for business owners to understand all of Google Guidelines, however as the old saying goes "ignorance is no excuse for not following the law".
The following is what I just sent one of my clients about duplicate content.
Google wants each unique article in one place on the Internet. Other wise they will consider it SPAM and will take your site completely out of Google.
This is the case if you have this duplicate content on your site and on others sites at the same time.
Another form of duplicate content SPAM is where the content is not on your site, however is on hundreds of other web pages. Then these sites could be penalized by Google and the links pointing to your site will not be counted as a vote for you by Google. Furthermore if Google saw massive abuse of the same content being placed on many thousands of web sites they may take even more severe actions to penalize the wrong doers.