Duplex Scale Tuning

[Johannes28@AOL.COM]

How do you tune the duplex scale?  I have plucked many grand pianos and 
noticed that the tuning is sometimes rather bizarre above the aliquots.  I 
know that Baldwin has adjustable duplex bars that allow you to tune each note 
as you choose.  However, most grand pianos do not have that kind of 
flexibility.  You have to move the ENTIRE aliquot if you want to change 
something.  (I've never tried messing with aliquots.)

But I wonder what purpose it serves to have notes flat or sharp in the 
duplex-system?  Flat or sharp meaning, if they DID sound in sympathetic 
vibration (which seems unlikely since they are not in tune with any notes) 
they would be off.  

And how come PETROF doesn't even use aliquots and their pianos sound good 
without them?  I know they use that German piano wire but then so do lotsa 
piano makers, piano makers who also use aliquots.  

Shouldnt we know how to tune the duplex-system to pass the PTG exam?  It must 
be important or piano makers wouldn't bother with it.

Johannes