Robbie asked:

 [ Are *pairs* of music rolls available (Primo & Secundo parts) for
 [ performance at two pianolas, or for piano and organ?

Aeolian Co did a very few - I've seen Piano I and Piano II for the
Greig concerto - and I've heard Denis Hall mention early
organ-plus-piano pairs but all the recent two-player performances I'm
aware of either use doctored complete-score rolls (Michael Broadway who
performs a lot in Italy has immaculately taped-over duplicates of
Rachmaninov's 2nd and Schumann's only concerto) or new pair rolls
specially cut from computer files.  Rex Lawson has made a number of
these - he's certainly done more but I can think immediately of a
Mozart two-piano sonata, Mozart's Jupiter symphony (first movement),
the waltz from Arensky's two-piano suite, Sir Charles Mackerras's
arrangement of Sullivan's Pineapple Poll Suite on two rolls (I mean
four) and of course Milhaud's Scaramouche.  The Sullivan is available in
full score for one player but as it's such a lively piece and in fairly
fixed tempo, it might be a goer commercially split for two machines.

I imagine in public performance handling these pairs is fairly
nerve-racking but if you're larking about they're wonderful fun.
Usually where one of the pianos has fewer than five bars or so rest,
the roll for that part continues in tempo with the bars marked in
soft-pedal dots on the right, but over that it becomes a waste of
paper, the roll restarts at the next entry and the performer has to
mark it up with some pencilled cues.  I noticed in the AMICA Chicago
Centenary Festival concert, Rex marked the rests on his specially-made
piano-part roll for the 1st Mendelssohn concerto with all of the
intervening orchestral bars written sideways across the roll with the
theme in top line notation (what d'you call it when the notes only show
the duration and not the pitch ? - that).  I should think if it's
twentieth-century music which isn't going to give you any help, you've
got to follow that pretty closely ! No sneaking out for a beer !

Dan Wilson