I'd be inclined to make the equivalent of a URL rewrite rule in the ASP equivalent of htaccess to only serve www.mysite.com. Sorry I don't know ASP so can't help with syntax there.
Then I would use canonical url to tell bots which page is actually the index.
Lastly I'd scan your site and ensure that all links on your site, which link to the home page have just a slash, as it's very likely there's a few of each:
This way all to the home page that crawlers see are just the canonical URL.
