In Oracle 10g version or earlier, while duplicating a database using RMAN, we had to connect to the Target database along with the Auxiliary Database. In oracle 11g, there is a new feature available, where in the duplication from the Target Database to the Auxiliary Database can be done using RMAN without connecting to the Target database or to the Catalog Database. Only thing what is required the full backup of the Target database.

You can use the below command for using this

rman auxiliary /

>duplicate database to newname from backup location '';

This will remove the dependency of you connecting to target datbase and will make you feel more comfortable when duplicating PROD database .