Terry Smythe asked about Dwight Porter's Twin Disk box.  Yes Dwight does 
build a twin disk version of his 15-1/2" 'Regina'-type music box.  I saw 
and played one recently while visiting Walt Bellm in Sarasota.  The two 
program disks contained the same program rather than separate coordinated 
programs as found on the 'Eroica' for example where 3 separate disks with 
3 separate complimentary programs played in synchronization for a wonderful 
orchestrated big sound.

I say Dwight does build the 3-disk; maybe I should have said he DID since 
I have no first hand knowledge that he still makes them.  As always 
Dwight's workmanship was outstanding on Walt's machine.