Recently i observed a problem in WordPress 2.7 related to paged comments. When ever someone posts a comment in our blog – the new wordpress 2.7 automatically assigns a link as “http://POSTURL/comment-page-1/#comment-number” which creates multiple pages with same content – A major problem for SEO.
So to avoid this , there is just one setting in your wordpress setting panel,
Go to your WordPress Admin panel
Then navigate to Settings >> Discussion Settings .
here you have to uncheck the “Break comments into pages” setting.
So from now your comments will be on same page and hence no duplicate content problem. Read my post where i have given few more tricks to avoid duplicate content in wordpress else Google will punish your site.
UPDATE : Steve written a amazing post with some tweak to wordpress files, which allows you to break pages with number of comments without harming the SEO. Take a look at the post : Dealing With Duplicate Content Issues on WordPress Comments Pages. The post is giving information about the Canonical URL meta, which allows us to redirect the bot to specific page so to avoid the duplicate content problem.
If you need more information of Canonical URL read a post of Google webmaster blog
But still if you prefer not to edit the PHP files simply use the trick that i have mentioned here at my post.
UPDATE: If you are using All in one SEO pack , then no need to do any changes in your wordpress, it is automatically using Canonical meta to avoid duplicate content issue.
Happy blogging … Comments are welcome