Duplicate Content

Duplicate content filters can be triggered by copied content, meta description and other page elements being mirrored, poorly configured blogs with entries filed in multiple categories, and articles that are distributed for backlinks and included in the author's website.

Duplicate content, if indexed at all will generally be found in Google's supplemental index and will rank poorly, or not at all.

ON PAGE SEO - BUILDING CONTENT
Never use the same meta description, title, and heading tags on multiple pages on a site. All the major search engines are smart enough to identify useless fluff or pages that serve no purpose.

WORDPRESS, DRUPAL, et al.
Blog's have unique issues that create potential duplicate content concerns. Build a blog entry and file it under four or five categories, and each page will be considered a duplicate content candidate when spidered.

The right fix is a bit nasty. The most common approach is to use robots.txt to prevent crawling and spidering the duplicate content. This works just fine, but the downside of this method is that any natural backlinks to these dangling pages wastes link juice.

A better solution is to use a meta tag like this one.

<META NAME="ROBOTS" CONTENT="NOINDEX, FOLLOW">

This will allow the page to be crawled, will not be indexed, and will allow PageRank to flow to other pages on your site based upon the links included on the page. Where this juice flows is up to you by adding a nofollow attribute to any links you wish to prevent juice flow. Link juice only flows to links that are not nofollowed.

SUBMITTING ARTICLES TO DIRECTORIES
A common mistake I see is creating an article, including the article in your website, and then submitting the article to directories and sites to build one way backlinks. The backlinks are a good thing. Although they don't carry as much weight per link, the sheer volume of backlinks can make article submission worthwhile.

The problem is that the article will be deemed duplicate content, as will the page on the author's site. This means that if the article ranks for keywords included at all, it will usually rank on the big article site, not yours. This also means supplemental hell for the duplicate content page on the author's site.

SUBMIT SMART ARTICLES
The perfect solution for this problem is to create teaser articles that will provide interest in the topic, and link to more in depth information on your site. This takes more time to create but results in traffic, indexed pages, and the backlinks that most likely were the underlying reason the article was written in the first place. This will also defeat any duplicate content problems for webmasters writing many articles.