The riddle only makes sense as such with one question in total.

The trick is to ask one guard what the other guard would say is behind a particular door.

I'm looking for something that does multi-device remote control similar to how Spotify does. Deezer just cancels playback on the other device.

No worries, you explained it well. People will grasp at straws to dismiss any argument if they aren't ready to examine certain convictions.

Would you believe it if they said that it's not actually that bad?