Can not differentiate which Com panel is being used when listening to VHF1 or VHF2

I want to determine only COM1’s listening status for VHF1 or VHF2. I used the SimVar Watcher and set the ‘COM RECEIVE EX1:1’ variable. However, when I activate the listening button for VHF1 on COM2, the ‘COM RECEIVE EX1:1’ variable in SDK also shows ON (which means when I listening to VHF1 in COM1 or COM2, the “COM RECEIVE EX1:1” variable all shows ON). I need to differentiate which Com panel is being used when listening to VHF1. How can I achieve this or is there any variable to achieve it?