Google May Be Fixing Issues With 301 Reirects
So this has been reported on before, the post that comes to mind is one by Patrick Altoft over at Blog Storm a while back. The idea is that Google is filtering certain types of 301 redirects in order to combat “bait and switch” tactics.
What I mean by bait and switch is when SEOs take a page that has a good amount of links and redirect the page to a product page, homepage, or wherever so that the new page can rank for the term that the old page did. Now sometimes the new page that the 301 is directed at is relevant to the old page, but sometimes it is not. And it is in this latter instance that Google gets offended.
It was noted that Google worked to eliminate this tactic (the latter in the previous paragraph) by implementing the Googlebomb algorithm a whle back. the idea is that if you 301 a page and the new page is not relevant to the old one, meaning the new page does not contain the keywords from the old on the page, then Google diffuses the passing of the anchor text(s). So the old page will still pass page rank theoretically, but it will no longer pass any keyword anchor text link value.
What does this mean to SEO consultants?
This means that if you want to take full advantage of 301ing pages with links to new pages, make sure that the two pages are relevant and that the new page contains the keywords of the old. It makes sense being that Google wants relevant results. It was too easy to manipulate the SERPs using 301s before. Now at least there is an order of relevancy.
You are right in your point, google is not now giving important on duplicate content, if you will use duplicate content then google just passed out and it will be effect in your rank.
I have come across to a scenario where 3 different urls are showing same content but all of them are ranking well.