Titles for WP feeds and categories

[Viktoria]

SeoMoz comes back with duplicate title errors. However these duplicate errors are /feed pages in Wordpress.

http://www.guardianpoolfence.com/choose-pool-fence/feed/

http://www.guardianpoolfence.com/how-to-choose-pool-fence/feed/

Why does this happening with only selected pages? I have many more posts but only these two are coming up with duplicate title errors.

Also how do I set up meta descriptions for categories and archive pages for example www.guardianpoolfence.com/2011/07

I am not sure how these pages were created and how to give these individual titles. I mean, titles at all...

Anyone?

[theideapeople]

My site gets penalties as well for the same WP issue. You can click on Categories to edit descriptions.