I didn't repeat this but I think there is a situation that will get two stations on different frequencies. Here is how this happened for me.
I sent a QSY request and also a text explanation of the motivation for the QSY in the same message. The other station saw the QSY request before the message was completely sent and immediately did the QSY. Since he QSY'd, my message never completed and I never saw my own QSY request.