I was surprised to see that google has indexed my homepage twice. I.e. one with www.mydomain.com and other with mydomain.com . The second url has been put in supplemental. (I have used site: mydomain.com). How can I fix this problem? Sitemap is already in place.
Choose one and make a 301 redirect via .htaccess file. In Google Webmaster Central, set your "preferred domain" to the one you're redirecting to.
Google usually indexes sites with same meta tags OR with duplicate content in to supplemental index. Do a 301 redirect and use google webmaster tools to set the preferred url.
Toss this into your .htaccess. Since you already have the www. in the main index, you'll probably want to just stick with that.
i strongly suggest you to read http://www.seo4fun.com/notes/supplementals.html tip. if you apply these tip , think you will get success
There is no need to read these tips...it's a simple canonical-url issue. There are two identical pages and Google is only indexing one of them. Just redirect the one in supplementals (non www.) to the one in the main index (www). Although that site has tons of info on getting out of Supplementals, this case is not that complex.