Won't devices like the ICD Shuffle Board allow you to do what you are asking?
http://amiga.resource.cx/exp/shuffleJust put a switch on the shuffle board's jumper.
This might work with the A500 and A1000. I don't know about any other amiga.
To Moderator sorry: I was trying to put this in the following thread: Dual floppy with a regular DF0 and a Gotek (with switch)
