In that scenario we will move catalog from stagecat(source catalog) to target database CLOUD.
[oracle@rmancatalog2 ~]$ rman target / catalog=rman/kjh7Rjsr1
Recovery Manager: Release 11.2.0.3.0 - Production on Wed Dec 21 09:28:47 2016
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: CLOUD (DBID=1801493836)
connected to recovery catalog database
RMAN> list db_unique_name all;
List of Databases
DB Key DB Name DB ID Database Role Db_unique_name
------- ------- ----------------- --------------- ------------------
49382 DB2 3896599226 PRIMARY DB2
49382 DB2 3896599226 STANDBY DB1
1 DB1 4139331099 PRIMARY DB1
1 DB1 4139331099 STANDBY DB2
SQL> select * from rman.rc_database;
RMAN> import catalog rman/U98wsjdw2#@stagecat;
Starting import catalog at 2016-12-21 09:36:33
connected to source recovery catalog database
import validation complete
Finished import catalog at 2016-12-21 09:36:40
RMAN> list db_unique_name all;
List of Databases
DB Key DB Name DB ID Database Role Db_unique_name
------- ------- ----------------- --------------- ------------------
548781 DB3 829073653 PRIMARY DB3
514674 DB4 1753676295 PRIMARY DB4
523618 DB5 3779067219 PRIMARY DB5
551022 DB6 4018492764 PRIMARY DB6
545408 DB7 4110887114 PRIMARY DB7
SQL> select * from rman.rc_database;
On the Source Catalog, the database will be automatically unregistered after the IMPORT CATALOG. If you need to retain the catalog on the source side even after the import then use keyword NO UNREGISTER.
Example:
RMAN> import catalog rman/U98wsjdw2#@stagecat no unregister;