I have an older Mac mini with 3 partitions: one running 10.5, 10.6, and 10.7. I'd like to back these up via Time Machine, however, I'd like them to each be separate backups. Whenever I try to back up one partition to the TM drive (with all other partitions excluded), it works fine. When I boot into a different partition and back up, it uses that same backup, adding the other partition to the mix.
How can I make them each use their own unique backups?