So is it that only when we create a clone DBID remains the same and not when we do export/import.
Thanks and Regards.
No. Even when you clone the database, the DBID does not remain same.
To be very much clear, the DBIDs would never be same as that of the target database irrespective of export/import or cloning. Only a standby database would have the same dbid as that of the production as it is a mirrored copy of the primary database.
In other words, we would never have control over the DBID and Oracle generates it automatically.
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As far as I'm aware you can't choose the dbid, you can force it to be changed but not what value to. Your only possible solution would be to restore the live database backup to the test box (without using rman clone i.e. either an rman restore as if the test box is the live box, or a straight copy of the files when live is in backup mode) - this would be a complete copy of live with the same dbid. I'm not 100% sure if the dbid will change if you just rename the database manually - so something like
create controlfile reuse set NEWDBNAME blah blah blah;
might work allowing you to rename the database from the restored copy of live but keep the dbid.
Generally though you don't want 2 database with the same dbid it's asking for trouble - i'd be looking to change any application logic that is checking it.