When running a Job Summary report the Duration column appears to display incorrect information.
This can be caused by multiple Jobs starting at the same time and the number of concurrent Jobs is limited to less than the number of Jobs scheduled. vRanger treats Jobs and Tasks separately. While the actual Task of running the backup may not start when the Job is scheduled to run the Job has started.
To get more accurate information about how long a vm took to actually backup run a Task Summary report. This will show the actual Start and End time of the backup for each vm.