and all my archive logs were of size not more than 500 mb.
If you have archivelogs going to two (or more) locations (defined by log_archive_dest_N where N is 1 to ...), Oracle may backup and delete any one copy. If you want to delete all copies, use DELETE ALL INPUT.
Before you do that do a LIST BACKUP OF ARCHIVELOG FROM SEQUENCE 4410 UNTIL SEQUENCE 4513 to confirm that one copy of each archivelog (sequence) has been backed up.
See the DELETE [ALL] INPUT documentation under backupSpecOperand at http://docs.oracle.com/cd/B19306_01/backup.102/b14194/rcmsynta009.htm#sthref141
Hemant K Chitale
@Hemant K Chitale yes you are correct. there are 2 locations where archive logs are stored. As you can see from my command i used delete input instead of delete all input. You have cleared my doubt, it was bugging me and got worried. relief now