RMAN-06216: WARNING: db_unique_name mismatch & RMAN-06218

When running a crosscheck backup in RMAN the following warning is presented:

RMAN-06216: WARNING: db_unique_name mismatch – 36 objects could not be updated
RMAN-06218: List of objects requiring same operation on database with db_unique_name RBTRAIN
RMAN-06211: ==========================
RMAN-06212: Object Type Filename/Handle
RMAN-06213: ————— —————————————————
RMAN-06214: Backup Piece 0ctdqbgi_1_1
RMAN-06214: Backup Piece 0ctdqbgi_3_1

To resolve, connect to RMAN with the credentials for the specified database and run a crosscheck backup on that database.

This is just an informational warning to remind you to crosscheck backups on the other databases in the catalog