Both those machines seem to be appliances that work in conjunction with a base firewall, like, a Barracuda NG firewall. I would guess that a typical setup would be Internet>>>>>Barracuda NG Firewall>>>>>Barracuda 300 Spam Firewall>>>>Barracuda 310 Spam Firewall>>>>>>>LAN.
Seems like a lot of hardware in a world full of hardware or software alternatives that do not require 3 devices. imo