Hello,
This ASCOM driver implements 2 different drivers in one single program "out-of-process". Software who want use these drivers must call "existing" driver. This means that client software must create a new driver instance if the driver is not running; but if driver is already running the client must connect to that driver (driver can be running for example when you start manually RF control panel interface).
You can try this, for example, using VBA in Excel and Word application at the same time: if you create instances for rotator and focuser in VBA Excel and in VBA Word you have only one application opened at time. Probably, software you are using create multiple instance of these drivers ad there is a conflict over serial port (low level driver uses the same access to the electronic device!).
We are working for a solution at the problem you have; at the moment I suggest to try use POTH downloadable to ASCOM website.
Best regards
Rotofoc Software Engineer