I am working for WP site. In webmaster tool it is showing duplicate content issue which is actually not because there are multiple pages generated through wordpress let me give you one example like
Both pages pointing at same page so how it should be fix which not be create so many other pages.
Please help.
Are you really a SEO school !!? 
just kidding
The issue is about the Canonical and all in one seo plugin you use on your website.
So try to Install the new version, or try this Fix : Link
Remember to always Backup your Database when you use a Codes !
Goodluck
Thanks @deadmix but i guess that is already added. Canonical links are already defined but still we are facing the problem WHY ?
Did you try with another SEO Plugin !? or try to deactivate the All in one SEO plugin then check again !?