Six maps, actually.
Present that sends you to Past with machine unbroken and Bad Future.
Bad Future.
Past with machine unbroken upon entry.
Past with machine broken upon entry.
Present that sends you to Past with machine broken and Good Future.
Good Future.
Of course, it'd be a whole lot easier if/when evaluation functions get put into the console (if boolean suchandsuch is true...), but since that isn't the case right now, six stages is a foolproof way of getting it to work. Foolproof, that is, with the exception of the absurdity of, well, six stages for one level. Yeesh.
Now, if we DID do the DarkWorld thingy that made the stages 4x as big, it wouldn't actually be a problem, because then all the warps could be modified then and there, so Present would send you to Good Future and the machine in Past would remain destroyed... but that could easily murder the BLOCKMAP, so...