I cloned my Vista drive to another hard disk in my computer as a bootable backup to cover myself when I upgrade to Windows 7 shortly.
However, it's been a while since I messed with multiple boots, so I can't remember if there's a problem having two identical disks in the system, and both being boot disks. (Actually, the new one on the SATA secondary connection.)
There doesn't seem to be a problem after cloning and rebooting to my original drive C, but I haven't switched and tried to boot the new disk yet.
I'm thinking it's not a problem, but would like to know the general guidelines, rather than running into a new problem firsthand.