You can determine that a grouped backup is underway from the progress report.

The keyword GROUPSIZE appears at the beginning of the batch file. This keyword indicates that NetBackup uses grouping to back up the selected SQL Server databases. If the appropriate conditions apply all operations are full database backups. Then all of the databases are snapped and backed up as a group. When this action happens, the progress log displays the backup image name as well as the storage image for each database in the group.