From my experience I've been able to open my virtual com port to my external bluetooth GPS device with two apps simultaneously, but both apps where having communication problems.
The best solution is to buy a port splitter software which installs virtual com ports and shares the gps (or other) com port.
In my experience only one program can use a BTport (or irdaport) at the same time.
And when you write a program, i you want launched an other program you must before write serial.openport=false if you don't want conflict.