Moving mobile sync to home laptop
You can back up as many iDevices to your computer as you please (technically). On my computer, I sync and have backed up at least three different iDevices.

All you need to do, is plug in your iPod Touch to your laptop, open iTunes, and back it up. It will know the difference between your iPod touch and iPad.

The difference comes in if you sync music from a computer (but that isn't relavent to this question, so I won't elaborate).