When using both DF0 and DF1 on AmiBench the disk changes are not always detected properly.
Usually this will happen if you try to change disks to fast. Example if you are installing an application that is on many floppies you might start with disk 1 in df0 and disk 2 in DF1, then when the installer asks for disk 3 you change df0 to disk 3 and then change df1 to disk 4 immidiately (before the system have detected the df0 disk change). At this point I have experinenced that none of the disks changes gets detected, and trying to change further disks may or may not work. At one point I opened Dopus and noticed it listed 6 disks mounted at the same time (disk 2 to disk 7), but these was not shown on workbench. And if trying to browse one of the disks in dopus made Amibench quit
In most cases this problem can be avoided by always making sure that the previous disk change is detected and updated on workbench before trying to swap next disk.
Although I once got the issue that df0 refused to change even if I gave it plenty of time to update. I managed to complete that install by only using df1.