Although the software tell you via error (message popup window) that only one instance of VARA is allowed, VarAC allows multiple instances of it.
Best could be to send a kill and allow strictly one instance no matter if user activates it.
If you close VarAC peacefully - it will shut down the modem.
But if you chose to kill it through the task manager, it doesn't given a chance to close the modem.
I do not want to put in place a mechanism where upon VarAC startup, it will already kill the modem.
1. If you want to have multiple modems running use different folders.
2. Not a good practice to run VarAC twice unless you are using different VarAC.ini files. There is a feature for this. Read this post for more information about launching multiple VarAC with difference configuration from the same location for a use case of dual monitoring on 2 frequencies.