Airplay to two devices

There is the option to use Airplay with more tha one device. This windows shows the two devices I have in my network. I can select them both. In Audirvana 2 this had the sure consequence that nothing happened: both devices remained mute. Now it’s better: One device plays the music, just one remains mute. Is this a bug or a feature?

EDIT: I was wrong. It’s the same as before: If I select both devices both remain mute. So I’ll avoid the cost for the update and stay with JRiver.