can't reformat 720K disks as 800K

[shack@deimos.frii.com (Randy Shackelford)]

I got a box of ~100 720K DOS formatted DD 3.5 disks which were about to be 
tossed at work, since DD disks are starting to get hard to find. My IIgs with
superdrive card and drive can see the disks as 720K DOS disks ok, but reports
an error when I try to reformat the disks as 800K ProDOS or HFS. It hoses
the existing file system, since the disks immediately cause the initialize
dialog to pop up on the Mac after the IIgs spits 'em out. The Mac can reformat
the disks pretty as you please, either when they're unrecognizable or by using
the erase disk menu option when the DOS disks show up. The IIgs happily uses
the disks after that. What gives? Is this a bug?
-- 
Randy Shackelford                                 
shack@frii.com