There are actually THREE different things that could be going on...
1. THE BUNKER TAPES which as Rob said is a live recording of the set in York
2. THE MACHINE STOPS soundtrack as a studio album
3. THE MACHINE STOPS live theatre performance which 'uses' parts of the soundtrack music but in a different order, looped and sampled 'live' in response to the action on stage
Although I must add that Number 3 above is purely speculative on my part, but (perhaps as a DVD) is the one I would look forward to the most if it were ever to be discussed.
Confusing? Of course