No webmaster wants to get hit with a duplicate content penalty. Especially because of something stupid like Canonical Content.

Canonical Duplicate Content is when you have a domain say www.yourdomain.com that exist as yourdomain.com as well. All pages under a domain can be considered a duplicate and actually hurt your rankings. the best thing to do is to 301 redirect traffic from www. to no www. or from no www. to www. Your choice really.

Duplicate Content Fix
Domain Base:	-dont include http://www.

*Only works on apache servers. Will not work on Windows IIS.