RMAN backups error while creating full & incremental backups - oracle

Question

We have our oracle instance running on windows server & when configured RMAN to take the backups we are seeing following error in the logs,
Error Details:
channel ch1: starting piece 1 at 07-MAY-17
channel ch1: finished piece 1 at 07-MAY-17
piece handle=\\backup_share\FULL_db01_20170507.BAK tag=COMPLETE_BACKUP comment=NONE
channel ch1: backup set complete, elapsed time: 02:10:37
channel ch1: starting incremental level 0 datafile backup set
channel ch1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ch1: starting piece 1 at 07-MAY-17
released channel: ch1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ch1 channel at 05/07/2017 23:10:45
ORA-19504: failed to create file "\\backup_share\FULL_db01_20170507.BAK"
ORA-27038: created file already exists
OSD-04010: <create> option specified, file already exists
RMAN Command Script:
run{
Allocate channel ch1 type disk format '\\backup_share\full_%d_%T.bak';
Backup incremental level=0 database tag='complete_backup';
Release channel ch1;
Allocate channel t1 type disk format '\\backup_share\ctrl_%d_%T';
Backup current controlfile;
Release channel t1;
}
I see same kind of logging when trying to take incremental backups. Could someone help me with this issue?

Answer 1

[oracle#orcluat ~]$ oerr ora 27038
27038, 00000, "created file already exists"
// *Cause: trying to create a database file, but file by that name already
// exists
// *Action: verify that name is correct, specify reuse if necessary
%d format specifies the name of the database and %T specifies the year, month, and day in the Gregorian calendar in this format: YYYYMMDD. It is also being reflected in your backup file name, FULL_db01_20170507.BAK. There might have files with the same name.
Better to use %U in your file name format which specifies a system-generated unique filename.
Documentation:
formatSpec