Last month Greg Grothaus an Engineer from Google search quality team speaks about what is duplicate content and how they treat website with duplicate content.
Here is the summary of the conference which was held at Search Engine Strategies San Jose.
How webmaster judge if their website is penalize in Google search?
He clearly mentioned that there is no penalty for duplicate content. The main reason webmaster thinks their website penalizes because sometime they find their website in omitted results. Actually web pages listed in omitted results are not penalize but Google want to show diversity in the search results. So, if Google find two different pages with same content and if you search for the specific keyword Google will show the important page for the keyword you typed in and omit the other page. What actually happen if you have two different pages with same printed content and if you don’t block page using robots.txt or meta noindex tag then Google will choose one from the list which it find more useful.
Here is the example of eight different URLs all are identical :
You will find many website have different URLs from same page. All URLs are different with same content. Google will not penalize your website for this but it will dilute your link popularity. For example if you have several website linking to one page of your site and some other websites pointing to other duplicate URL cumulate link juice. Also search engine get confused in selecting the user-friendly URL and sometime show up wrong URL that offset your branding efforts. Other problem is inefficient crawling because Google crawling the same content for different duplicate pages and give less time to the new pages.
To avoid duplicate content issues use the following steps
(1) Canonical Version: Here you can specify the page which you want Google and other search engines to crawl and ranked.
(2) 301 Redirects: This is called permanent redirect means redirect duplicate pages to your preferred URL.
(3) Also in Google webmaster tool specify version of your website with WWW or without WWW.
Multiple Site Issues
Use different domain names for different country. Write different content for different audiences because here also duplicate content issue affects your ranking in search engines.
If you have same content website for different audience let say for Australian audience and British audience Google will show only one website.
To avoid this problem you need to specify your website region in Google webmaster tools.