The AnywhereUSB models that support the MHC (Multi-Host Connections) feature will allow other computers to connect to other USB devices attached attached to other USB ports, at the same time that your existing server is connected to your existing dongle.
It sounds like you're asking if you can "share" a single USB port/device (a dongle in your case) and the answer to that question is no. USB ports and attached USB devices cannot be shared. They can only be connected to / used by one computer at a time.
A workaround you might want to try is to have the new server "take turns" with the existing server, connecting to the AWUSB/2. In other words, have the server that needs to use the dongle connect to the AWUSB/2 on an as-needed basis. This is analogous to physically removing the dongle from one server and connecting it to another, if you can imagine a scenario where you have 2 servers physically near each other that both need to use the dongle.