I wrote simulator originally only for sending and have only as plans to extent it. But before that you need two different ports.
There is also virtual com splitter hub4com, which I use for other purposes. I have not tested could that be used with ActisenseListenerSender so that example reads and writes to same port, which would be then splitted with hub4com for Actisense Reader and Simulator. It should, since my use is pretty similar. That may also depend of hw, since when I started some years a ago with Mega and Due, I had problems to get ports reliably working both directions with lot of traffic.
During developing I have several Teensys on same bus - one listening with Actisense Reader, one sending with simulator, one filling up bus traffic as standalone, one just for proofing address claiming and naturally the devie under development, some devices (MFD, log) from boat in winter time. So the bus is pretty full of traffic to test that library and other code works. In this way do cross checking for devices and library code.
For real testing I prefer to use separate devices.
By the way, where you got the name Kvaser? I have never used those devices and simulator supports only Actisense format on sending.