This used to happen to me with my old Marantz players and Arcam amps. The volume used to change on both so I had to manually change the volume on the amp.

Also more recently I think the play button on my Meridian CDP also starts playing my Linn streamer but I might have got mixed about this one.

The solution is to walk over to press those buttons on the unit, or if there aren't buttons then to block the sensor on the one you don't want to react, I think a hand usually does it for infra red.