[Mac86]

I am new to Superduper (and making bootable HD copies etc) and trying to familiarize with the features. So I apologise if this has been covered before (tried to find it)
If I make a bootable clone of my Powerbook G4 HD (running 10.4.11 and classic) on one partition (journaled) and if I make another partition for Sandbox (journaled to make it bootable), will there not be a conflict for the laptop during start-up as it would try to start from both systems? Is that a bad idea?
I am trying to make bootable HD backup and then replace my internal-dying-hard drive with the new one and have the Sandbox in place so that I can avoid doing this again after the event (such as fatal errors accumulating in the HD).