With vCenter or ESXi there is no trust needed. NO Backup Exec Agent required to backup up VMs from either vCenter or ESXi.
The issue here is how do you get a catalog and Backup file from one media server to another. Well, you can manually copy all the Backup files to your other media server and inventory catalog them. Or you could use the CASO option.
CASO allows for a centrally controlled Backup Exec setup. You could backup from the Central Media server and restore from one of it's Managed Media servers. Or you could backup from the Managed Media Server and restore from the Central Media server.