The last "license" problem I had was with 3.5.0. I own a BTV license and two BTV Link licenses.
I had two Link machines that were using DHCP. After doing some reboots, I might get a message that another computer on the network was using the same license key.
I was able to reproduce the issue by doing a shutdown of both Link machines, and then starting the machine that had the larger IP address. When it came up, it received the lower IP address of the other Link machine. The BTV Server had been up the whole time. When I tried to connect to it, I would get the license key error message. It thought there were two IPs using the same license key ... although it should have throught that there were two licenses for one IP too ... but that is just good Sales.
I quickly switched the Link machines to static IP and have not seen the error since.
So, back to your question... based upon what I saw, I think you would get an error message from BTV when the 2nd machine attempted to connect. When the BTV app is shutdown and restarted on the server, it seems to forget which machine had which license.