PROBLEM:

While duplicating a database using RMAN active cloning in RAC database, got below error.(ORA-65500)

RMAN-03015: error occurred in stored script Memory Script 
RMAN-03009: failure of sql command on clone_default channel at 1/02/2017 21:40:59 
RMAN-11003: failure during parse/execution of SQL statement: alter system set 
db_unique_name = 'DBATEST' comment= 'Modified by RMAN duplicate' scope=spfile 
ORA-32017: failure in updating SPFILE 
ORA-65500: could not modify DB_UNIQUE_NAME, resource exists 

SOLUTION:

If you are creating a RAC auxiliary, then it must be created as a single instance (with RMAN) first, then converted to RAC.

1. set cluster_database=FALSE in the auxiliary database parameter file

2. Remove database resource from CRS

srvctl remove database -d DBATEST

SEE ALSO – RMAN ACTIVE CLONING FROM RAC TO RAC

SEE ALSO – RMAN ACTIVE CLONING IN ORACLE 12C