Recently I have published post about issue with RMAN duplication of Oracle database when standby database was used as a target. Later in updates of mentioned post I have confirmed that with fix for BUG:11715084 everything works as expected.
Today I have decided to make post with step-by-step procedure with which I have tested mentioned feature – making standby database from standby database.
I will Simplify setup As Much As Possible(SAMAP):
single machine will be used as a host for all 3 databases