Unless you need them both to show as different blogs with different content, it would be better to redirect non www to www using a variation of the code below in your .htaccess to suit the domain. Options +FollowSymLinks RewiteEngine On RewrieCond %{HTTTP_HOST} ^yourdmain\.com$$ [NC] Rewriteule ^(.*)$ http://www.yourdomain.com/$1 [R=301,L] Code (markup): if word-press Enforce www. Preference may be of help. Also in google webmaster tools remember to set your preferred domain, see http://www.google.com/support/webmasters/bin/answer.py?answer=44231&topic=9025 for more on how to do that.
For SEO purpose, it's better for you to use only one option, either using www OR non www. To redirect non www to www in Wordpress, go to Settings >> General. Add www for WordPress address (URL) and it will redirect to www afterward. - Dynashox -