This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
I have three Duodisks. The one connected to my flagship ROM 3 IIgs has had the resistor and capacitors clipped out as recommended in a memo from Mitch Spector. It works perfectly! ---------------------------- By: Rubywand A Duodisk may not be entirely functional connected to the usual ROM 3 "Disk" connector (i.e. the SmartPort). Users report that the system may not start up unless a write-protected disk is inserted in the Duodisk. Apple, in Tech Library notes #5010 and #5434, mentions these reports and says that there is some code in the ROM 3 ROM that does not handle the interface to a Duodisk properly. Apple's workaround is to connect the Duodisk to a drive interface card instead of to the Smartport. By: John L. Graham