Reindexing a site with www.

[JohnW-UK]

We have a site that has a mirror - i.e. www.domain.com and domain.com - there is not redirect both url's work and show pages so basically a site with 2 sets of URLs for each page. We have changed it so the domain.com and all assorted pages 301 redirect to the right URL with www. i.e. domain.com/about 301's to www.domain.com/about

In the search engines the domain.com is the site indexed and the only www. page indexed is the homepage. I checked in the robots.txt file and nothing blocking the search engines from indexing both the www. and non www. versions of the site which makes me wonder why did only one version get indexed and how did the clients avoid a duplicate content issue?

Secondly is it best to get the search engines to unidex domain.com and resubmit www.domain.com for the full site? We are definately staying with the www.domain.com NOT domain.com so need to find the best way to get the site indexed with www. and remove the non www.

Hope that makes sense and look forward to everyone's input.

[WesleySmits]

First off you should go to webmaster tools and make sure that you have verified that you are the owner of both the www and non-www version. After this you can tell Google your preferred version of the page under the site settings within webmaster tools.

This by itself will tell Google that it should index the preferred version. Furthermore you said that the non-www redirects to the www version now. Google will pick this up in time and will start indexing the www version.

Your question about why only one got indexed is hard to answer like this. If it's not the robots.txt than it could be a link rel="canonical" pointing towards the non-www version?