RAC database with 2 instances on a single server

I've a requirement for our internal testing. I need to create a RAC database with 2 instances in a single server without using VMWare or something else.
Its like, i'll install the clustureware in the server and instead of single instance per each node, i need to create 2 instances in the same server for the same database.
It might be possible, but i need some suggestion on how to proceed.    

Thanks,
Sandeep  

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