Create a file/variable holding your client list... than
for each client run
bpimagelist -client $clientname -d startdate -e enddate -l |grep "^FRAG ? 1 " |wc -l
this should give you the number of backup images... but I am wrtinting this from the top of my head...
you can lookup bpimagelist here https://www.veritas.com/support/en_US/doc/123533878-127136857-0/v123538598-127136857