Does Backup Exec support Multiplexing/Multistreaming?
Multiplexing (or multistreaming) allows multiple streams of data (such as backups from two remote agents) to be written to the same backup media simultaneously. If the speed of remote agents is a bottleneck (and the speed of the media isn't), then multiplexing can provide performance improvements.
Backup Exec does not support multiplexing. Symantec NetBackup does, however.
The closest parallel in Backup Exec is the ability to write multiple jobs to a Backup-to-disk folder. This isn't the same as multiplexing, and it's only relevent for disk-based backups.