Duplicate content can get you in a heap of trouble. Once in grade school, I repeated, out loud, what my friend whispered in my ear. The next thing I knew, I was in the principal’s office and my mother was “leaving work early”. Having duplicate content isn’t going to bring down the wrath of your mother or her wooden spoon, but it will land you in Google’s office if you are doing it deliberately.
Duplicating content can also affect your site in a variety of ways, like hurting it’s bandwidth. Duplicated content can lead to inefficient crawling by the spiders.When they discover ten URLs on your site, it has to crawl each of those URLs before it knows what is the same content or not. The more time and resources spent crawling duplicate content across multiple URLs, the less time it has to get to the rest of your other content. Thus, slowing down your bandwidth and possibly upsetting the Google gods.