Prevent Spiders From Crawling Duplicate Content in Wordpress
Update your robots.txt with this information to prevent some of your pages from being crawled by polite spiders:
User-agent: *
Disallow: /wp-
Disallow: /search
Disallow: /feed
Disallow: /comments/feed
Disallow: /feed/$
Disallow: /*/feed/$
Disallow: /*/feed/rss/$
Disallow: /*/trackback/$
Disallow: /*/*/feed/$
Disallow: /*/*/feed/rss/$
Disallow: /*/*/trackback/$
Disallow: /*/*/*/feed/$
Disallow: /*/*/*/feed/rss/$
Disallow: /*/*/*/trackback/$