oracle job duration is not correct

hi friends

i use netbackup 7.5 and opscenter for reporting. type of some of policies are oracle database. and they have several channels to do the backup.

when i use job duration report for the policy it sum measure of all channels. for example i know job duration must be 40 hours but becouse of 5 channles it show me 200 hours.

is there a way to count exaclt measure of this kind of policy?

Thanks

Best Regards