RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 01/17/2017 11:02:45
RMAN-05501: aborting duplication of target database
RMAN-05520: database name mismatch, auxiliary instance has PROD, command specified CLONE

Cause: Cause:

I started the duplicate while instance is in nomount and duplicate returned into error after mounting the database due to no backup or found. This duplicate was triggered after connecting to both target and auxiliary instances. During the clone RMAN will begin the clone instance with the target instance name (its PROD in my case) and proceed with the duplicate. When the duplication is successful it will clone the database with the auxiliary instance name. Since the duplicate resulted into error it left the instance with target instance name (PROD).

Fix :

- Just shut abort or immediate the auxiliary instance.
- Start the auxiliary instance (CLONE) in nomount using pfile
- Re-run the duplicate