Multiple URL's on first page of Google

Multiple Url, Multiple Domain Names

[Coughy]

Greetings,

The website I am working on has multiple domain names. A couple months I had changed the DNS settings for the "alternate" name as I was having a problem. In the past two weeks I redesigned the site a bit. Today I was happy to find that the site had increased in rank to 4th on Google. Normally I would be very happy, however I have noticed that the other domain name for the site also has appeared on the bottom of the first page of google. The domain name I am used to seeing in google appears as "www.mydomainname.com" and the alternate domain name has appeared as "www.myotherdomainname.com/index.html". Previously the second domain name did not appear in google at all......how concerned should I be and what should I do if anything to avoid having problems with google?

I would greatly appreciate all help in this matter....tyia

[wheelie34]

That would depend on what content is on both domains, is it the same content/niche/topic?

[Coughy]

Both domain names are pointed to the same ip address.