Duplicate Content Penalty

[Julz34]

Do all se's penalize sites for duplicate content? Can you create mirror sites to run separate advertiser's ads on?

[goodroi]

Welcome to WebmasterWorld Julz34!

Launching mirror sites is not a good idea. I don't know of a search engine that enjoys duplicate content.

[medowl]

In theory the SEs penalize duplicate content, but in practice, this is not always the case. For example, I did some original research and published it on my website. There is a link to my work on wikipedia. When I search for that niche term on some the major search engines, there are several wikipedia scraper sites on the first page of results; these outrank my article when they are not only duplicate, but also much shorter and less relevant to the niche search term.

In the long run (in an ideal world), these scrapers should be demoted or dissappear. The SEs are more likely to penalize duplication that occurs on one identifiable site than that scattered across the web. But they are not very good at dealing with duplicate content in the short run.

I wouldn't invest in that type of content when original content is more likely to be stable.

[Julz34]

Would you suggest posting original content on article directories that are also pages of my website? If so, then how many would be acceptable? 10%, 20%, 50%, 100%

Example:
Total Original Content Pages = 30
5 out of 30 pages = 16.67%
10 out of 30 pages = 33.33%