[rescue] imaging old Mac double density floppy disks

[kevin]

Lately, i've been trying to image a bunch of Macintosh formatted 
DD (double density) floppy disks using my x86 linux box.  It 
seems to work like a charm for the HD floppies but none of the DD 
floppies work.

Someone told me that the old Macintosh DD floppy drives (not the 
SuperDrives of days past) were "special" and that it was not 
possible to read older Mac formatted DD floppies using a PC 
floppy drive.  Anyone know if there is any validity to this?  I 
thought that none of that would be relevant if i was using dd 
(i'm not mounting the disks, just trying to image them).

I'm using the following:

$dd </dev/fd0 >./mac_floppy.img

Any ideas?

Thanks,
K