It seems that with the infiltration of spam sites and splogs into Google’s search index, they came up with a duplicate content filter to solve this problem. These spam sites use automated tools to scrape content from other websites with the hopes of creating keyword dense pages that rank high in the search engines and make money through AdSense or other advertising. If Google finds two websites with the exact same content, this duplicate content filter will put these pages into Google’s supplemental index. Once a page goes into the supplemental index, it is removed from Google’s regular index where it usually won’t rank. What happens next is the slow death of these web pages and potentially the entire site.
If you syndicate your blog’s RSS feed through FeedBurner, you could have a duplicate content problem. Here’s how to check. First, search Google with the operator site:www.YOURDOMAIN.com. If you see any of your pages in the supplemental index, login to your FeedBurner account. Under the “optimize” tab, select the “browser friendly” service. Make sure that your content options list the item titles only. If you have it set to list item titles and content and Google spiders and indexes your FeedBurner feed, then you’re essentially duplicating your own content. Not good if you want to be found in Google’s search engine results.
If you syndicate your blog through any other service, like ziki.com, stop. These sites mean no harm, but they aren’t search engine friendly. In fact, they are detrimental to your blog’s life in the search engines. Beware.
Most splogs don’t stick around for long so if they’re copying your content, they’ll probably be booted from Google pretty fast. But you never know so you should check. Visit copyscape.com and double check that your content isn’t being violated.