What is repeating content?
It’s basically another page on your site, (internal repeating content) or on another site (external repeating content). Repeating content is bad because Google and other search engines, treat the repeating content with contempt!
Any repeating content is particularly targeted by Google’s robots, indexing your site, displaying the following message: “Search Results Omitted”. The short of it is that instead of getting two or more rankings on one page, you have one. Less presence.
So how do you know if you have duplicate content?
Look for warnings in Google Webmaster. Google Webmaster is a free service that gives you an inside view into how Google sees your website. Google Webmaster will tell you if you are being penalised for duplicate content.
Alternatively, use http://www.copyscape.com to check you site for external sites, copying your content.
Obviously, you need to write your own copy, for your own benefit. Make it unique, interesting and full of key words and search engines will optimise your results.