The Reseller Backups bandwidth is charged to that Reseller's bandwidth.tally file.
Each user being backed up is not charged for that bandwidth.
It sounds to me like the bandwidth was not reset on your system. Type: Code:
echo "action=reset&value=all" >> /usr/local/driectadmin/data/task.queue /usr/local/directadmin/dataskq d
to reset everyone back to zero.
If you want to remove bandwidth counting for that particular backup, then remove that bandwidth entry from the reseller bandwidth.tally file after the backup is done (no DA option to disable it)