Duplicate Page Titles & Content Warnings

I recently signed up for an account with SEOMOZ.org to start getting into doing a better job at SEO for my site. SEOMOZ is giving me duplicate page title and content warnings for every blog posting that I have. One example is the following URLS:
http://www.productsforautism.com/blog/10/contactus and http://www.productsforautism.com/blog/10/early-childhood-evaluation. They both of the same title. I don't know why the first one even exists, but you can browse to it. I am also getting the same problem with my category pages: http://www.productsforautism.com/c/21/contactus and http://www.productsforautism.com/c/21/language-arts. Anyone have any ideas why the contactus page exists in these cases?

Does anyone have any ideas on why there is a /contactus page for each blog page and product review?

I have a similar issue on the blog pages where they are showing up as duplicate content as although the url changes for each post, the meta title and content remain the same.

Is there any way to change the titles as there isnt an seo tab as with other content on the admin section.

Alternatively is there a way to add a canonical tag on this page?