There were problems with the old SQL in mk_oracle for the RMAN check. The result are a lot of false alarms. This issue has been fixed with a new strategy in selecting the data.
This is an incompatible Change when ORA
This change requires a modification of existing rules due to change names for the checks.
Please don't forget to rediscover the RMAN checks.
There is a global variable which can be used to switch to the old behavior. Details are documented in the manpage.