Duplicate PDB backup with RMAN

Oracle RAC 19c with 3 nodes on OracleLinux 8.6.
I backup PDBs with RMAN, the backup files are duplicated in the same save directory.

Again with RMAN the full backup of the instance and the backup of the CDB$ROOT are performed correctly.

This is the RMAN comman used for one PDB backup:

RUN {
allocate channel d1 type disk format '/bckacfs/CDB/DIP/backup_full_%d_%T_%s_%t';
allocate channel d2 type disk format '/bckacfs/CDB/DIP/backup_full_%d_%T_%s_%t';
BACKUP PLUGGABLE DATABASE dip
format '/bckacfs/CDB/DIP/backup_full_%d_%T_%s_%t'
(database);