How to remove duplicate content on my bog?

I found out that two different pages on my site are "81% similar". I used http://www.webconfs.com/similar-page-checker.php to check this.

The two pages are: www.mysite.com/keyword and www.mysite.com/page/3

The first page has an original article I added and the other page has the same exact article but I don't know how the page was created.

Any ideas?

I'd also like to know if there's any software that will scan my site and find other possible dupe content.

I wonder how did you scrape the article?

I know there is an rss aggregator yahoo pipes that can make each post unique by its primary key

It be the link you harvested,the title of the post,the description