Add Tags in Admin

Hi,

I’ve just got a report from SEOmoz and it is showing a lot of duplicate pages. However, I don’t have any dupe pages or posts. What I have found is duplicate tags. Here is an example

http://www.isabels-typing-services.co.uk/blog/tag/market-research
which also has-

http://www.isabels-typing-services.co.uk/blog/tag/interviews

and every other tag seems to create a new url linking to the same article.

What am I missing?

Thanks