Google indexing trackback URLs

Hi, i have a WordPress blog. Yesterday i came to know that Google is indexing trackbacks of my every post. For example

http://example.com/2010/05/post-title/trackback/

I am very worried about the situation as this is creating duplicate content issues. I have already installed “no-self-pings” plugin and have disabled the following two options in Discussions tab in wp-admin:
–>Attempt to notify any blogs linked to from the article (slows down posting.) [Disabled]
–>Allow link notifications from other blogs (pingbacks and trackbacks.) [Disabled]

I have also blocked trackbacks are feed URLs via my robots.txt

Disallow: */trackback
Disallow: */feed
Disallow: */comments

How can i completely disable this trackback and ping option in WordPress, also i want to remove “Allow link notifications from other blogs (pingbacks and trackbacks.)” on my all previous posts.