I suppose you can try to use a router, but conflicts can occur when doing this. Drivers can conflict, and you are more likely to have more errors and slower connection speeds. And also, consider this, the Broadband is a 5 GB plan. If two people were using the device and, if possible, the same time, you are going to use up those GB far faster and could result in a hefty bill.
You can use the Broadband card on two different devices. Let's say you are using the internet on your desktop and then want to use your laptop. Simply disconnect from the internet on your desktop, take out the Broadband modem and then plug it into the other computer.