Question about Sony Mdr-Rf895rk

I have two sets of headphones, one connected to my wife's computer, one to my computer. No matter how I set the channels, I always have to listen in to what my wife's computer is transmitting. In this sense, it should be possible to operate more than one pair of headphones from one source. But I imagined it differently...

I cannot try this. There is nothing in the instructions about multiple headphones BUT the sentence "3 transmission channels available".