No we only support 1 USB drive at a time.
You can use FTP to access the Drive and move content on to it. If you already have a PC setup with DashBoard for your Menu System you can add the switcher as a "Network Drive". Now you can go through the Folder Structure of the USB and Drag and Drop.
Further under the Sets folder of the drive you can now also rename File set folders or even create new folders that will allow you to see this from the switcher UI as location to save to.
Les
#Carbonite