As far as I can tell you will have to aquire a bluetooth transmiter that will allow the parallel connection of two devices. If you write 'How to connect 2 wireless headsets to TV at the same time' in Youtube or Google you will likely get to what I mean, as I can't discuss makes over here.
An advantage in Android 9 is the possibilty to connect several audio devices at the same time. It does not exist in Android 5.