You could always just use two different images and two different emulator configurations. Do you use basilisk? On Linux? Then copy the file ~/.basilisk_ii_prefs to ~/.basilisk_ii_prefs2. Open the file and change the "disk" option to the right image.

Then boot like that:

Or, for thew other configuration:

Or just give the disk option directly:

or

I don't know any software that could do it like grub or so.