yeah, it connects to the phone via wifi, but I haven't done any packet analysis beyond that to see if they each each have a unique ssid, or maybe they're going by MAC address, which is an easy enough system.
Aside from these dongles, I have enough of a headache when my wife & I start both of our cars to go different places, ad her phone likes to connect to the wrong car (mine). Then I have to drop her connection from my dashboard, and switch it over to my phone.
First world problems, I know