About multiple volume groups (Multiple robots)
A profile only ejects media from the robotic volume group of the vault to which the profile belongs, and a volume group cannot span robots (typically, a volume group identifies a specific robot). However, a profile can select images to duplicate that are in a different robot's volume group and in multiple volume groups. This ability is useful if you have backup images on multiple robots and want to duplicate those images on media in a robot from which the media is ejected.
If you use this configuration, configure it with care.