I’m not sure what is going on by lately I’ve had a string of clients all with serious issues with duplicate content. One client even claimed he had SEO-ed his site. He version of SEO involved pasting all of his pages’ content onto other sites. The result for this SEO site was it couldn’t even rank in the top 200 for a low competition localized term. I feel I must repeat myself…Google hates duplicate content! I believe part of what is causing the ongoing duplicate content trend is that there are some SEO companies out there that claim that building multiple sites all with the same content will get you multiple rankings in the top ten. The problem is Google hates duplicate content and this will not only cause you not to have multiple top ten rankings but you will generally loose the current rankings you have.
Just so you know, if you make this kind of mistake, it is an automated penalty that Google will hit your site with. So if you remove the duplicated content Google will forgive you. From my growing experience in this it seems to take 2-4 months for Google to forgive. There are several factors in this which include competitiveness of the term, page rank of the site (which influences how quickly Google will notice the change), and how many times the content was duplicated.
Resolving the issue of duplicate content involves testing your pages. Traditionally, I would use Google to find duplicate content. This involves grabbing a few lines of text from a site then searching in Google using quotes around that text. However, this doesn’t always work. Spun content will not be detected this way and it can still impact on your rankings. This is why I recommend using Copyscape.com which allows you to enter your URL and check if there are any duplicate pages on the web. It is a very simple tool and shows similarities even with spun content. The more results in copyscape means the more that your page has been copies. So the goal is to make it that copyscape shows no results for a page in question. I also recommend not just testing your homepage but to test all of your major pages.
If you are experiencing problems where your rankings are affected by duplicate content penalties, please feel free to contact me.