How to SEO multiple domains for one site

We like to know your opinion about following problems:
We have one site http://manausbooking.com and several other related domains with the same content like http://amazontoursmanaus.com or http://amazonhostel.com
If you put the same content on different domains get the main domain punished by Google or Bing?
What is more effective to push page ranking of each domain?
a) same content on all domains
b) forwarding with masking
Thanks
How to SEO multiple domains for one site

See original post by tropicalconsulting