On multi channel backup backups with RMAN using HP DP the channels are closed per default after 30s from HP DP.
If you backup all archivelogs then try to backup the controlfile the timeout gets hit often.
As consequence the backups are market as failure in RMAN and as success in DP.
Set HP DP Timeout to a higher value (like 15 Min or more) in the globals config file ( /etc/opt/omni/server/options/global)
and restart HP DP
omnistat omnisv -stop omnisv -start