In order to use more than one tape device simultaneously, you will require, a Library Expansion Option License, otherwise the 2nd library won't display in BE. This way you can configure device pools i.e
Pool 1 Library 1
Pool 2 Library 2
When you configure the backup jobs, select which device pool required by that job in Devices & Media
From Network & Security, select the NIC associated with the VLAN to which the target server belongs.
If a DNS server exists in each VLAN, you will need an A record in the zones, so that the Media Server will correctly resolve servers in each VLAN.