SAP redirected database restore using brrestore/rman_util failing

We are trying to restore the backup of an SAP Oracle database on an alternative client. The backups are made through brtools using the rman_util option.

I followed the directions for mentioned in the Netbackup SAP guide. I'm able to list the backup images using bplist and restores of the control-file through backint works. But when we want to restore the datafiles through rman we get the following errors:

channel sbt_1: ORA-19870: error while restoring backup piece HC2_beqfhgua.16701_1
ORA-19507: failed to retrieve sequential file, handle="HC2_beqfhgua.16701_1", parms=""
ORA-27029: skgfrtrv: sbtrestore returned error
ORA-19511: Error received from media manager layer, error text:
   Failed to open backup file for restore.

The restore job is visible on the media-server and failed with error-code 2811 and the following information:

08.04.2015 14:35:10 - begin Restore
08.04.2015 14:35:11 - restoring image IMAGENAME
08.04.2015 14:35:11 - requesting resource @aaaab
08.04.2015 14:35:12 - Info bprd(pid=9188) Restoring from copy 1 of image created 04/05/15 00:12:00 from policy SAP_HPUX_DB_ONLINE
08.04.2015 14:35:12 - granted resource MediaID=@aaaab;DiskVolume=PureDiskVolume;DiskPool=DP-p02bck-Dedup;Path=PureDiskVolume;StorageServer=nb-servername;MediaServer=nb-servername
08.04.2015 14:35:14 - Error bpbrm(pid=8816) bpcd on hc2db00.domain.name exited with status 39: client name mismatch   
08.04.2015 14:35:14 - Info tar32(pid=0) done. status: 39: client name mismatch       
08.04.2015 14:35:14 - Error bpbrm(pid=8816) client restore EXIT STATUS 39: client name mismatch     
08.04.2015 14:35:15 - restored image IMAGENAME - (client name mismatch(39)); restore time 0:00:04
08.04.2015 14:35:17 - end Restore; elapsed time: 0:00:07
SAP policy restore error(2811)

Found technote TECH193578, but this one is telling me that it only works for file_util, not rman_util.