Does Disallowing a directory also tell search engines to unindex?

[Ocularis]

I have a bunch of duplicate pages/duplicate title issues because of Joomla's item/category/menu structures.

I want to tell search engines not to crawl, and also to unindex anything in those directories in order to solve the duplicate issues.

I thought of disallowing in robots.txt, but then I realized that might not remove the URLs if they've already been indexed.

Please help me figure this out.

[HiveDigitalInc]

Yes, this will remove them, but if you want to speed up the process you can use the google URL removal tool http://support.google.com/webmasters/bin/answer.py?hl=en&answer=164734