The dangers or RMAN Autocataloging...

In later versions of RMAN (at least 11g) when you perform certain types of database recoveries and duplications RMAN will catalog the backups for you. This is handy if you have a newly recovered control file, since it will get all of the archived redo logs and backup sets cataloged for you.

I do a lot of RMAN testing where I create databases, drop them, re-create them, recover them, etc... I've noticed that this can have some odd impacts sometimes if you have old backups or archived redo logs from a previous version of that database. Say, for example you create an ORCL database, do a lot of stuff with it, delete it and create a new ORCL database. Sometimes RMAN will get weirded out when it tries to catalog the old backups or old archived redo logs.

I have not taken the time to try to figure out all the dynamics on what is going on here but I would recommend that anytime you remove a database and intend to re-create it, that you move the backups and old archived redo logs out of the FRA or the archivelog destination directories somewhere else if you need to keep them. This will make your RMAN life much easier.