Google's Matt Cutts Discusses Meta Descriptions

A "meta description" is a meta element used to provide a concise explanation of a web page's content, and is widely supported by the leading search engines. In this video Matt says that having no meta description is better than having duplicate meta descriptions. And if you are short of time or resources, he advises that you should concentrate on the meta descriptions of just your homepage or other important pages.

If your website was built by SiteCenter, your website will definitely have a meta description on every web page that is to be included in search engine results, and since these are usually dynamically created from the web page's content, none of these will be duplicate unless you have created two or more of web pages that contain exactly the same content.