Google Indexed AdWords URL - Now What?

[panana]

Hope everyone is having a great year so far. I've run into an issue that I was hoping to have help with. Here's the story:

My client added on a service and bought a keyword filled domain to use for AdWords purposes. I set the robots.txt to exclude all robots from the AdWords domain.

Today, the AdWords domain suddenly showed up ranking highly in Google for one of the keyphrases of the service. I guess Google ignored the robots.txt.

Now - we have a page on the main site that has the duplicate content of the 1 page on the AdWords domain. What should I do?

Use the robots.txt file on the main site to exclude the duplicate page and hang on to the AdWords domain rankings?

Or try to get the AdWords domain excluded from Google through further action, such as using the robots exclude on-page?

I'm leaning toward keeping the the 1st solution, however a 1 page domain may not be the horse to bet on. I'd appreciate any opinions.

Thanks for any help that can be offered -

[AussieWebmaster]

you should be able to get it out of google by adding a no index in the meta tag of the page

[panana]

Hey Aussie -

Thanks very much for your reply. The big issue, though, is whether I should try to hang on to the rankings won by the AdWords domain. Any opinion?