No need to worry about duplicate content in different Domains Now. You can use Canonical URL to solve this problem.
Sometimes, There are situations where it’s not easily possible to set up redirects. This could be the case when you need to migrate to a new domain name using a web server that cannot create server-side redirects. In this case, you can use the rel=”canonical” link element to specify the exact URL of the domain preferred for indexing.
Google has announced its support for using the rel=”canonical” link element across different domains. Yahoo and Bing have not (yet?) announced cross-domain support for the rel=”canonical” link element.
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