Can CanoScan be installed on two computers?

Its not easy to share a scanner in Windows as you rarely get the sharing tab when you click on the scanner properties. However there is a free app called SaneTwain that works really well.

Google saneTwain

Most scanners including all-in-one printers can be shared acrossed a network. Hook up the scanner to one computer. At that computer, go into the control panel and to scanners (XP that would be printers and other hardware and then scanners). Right click on the CanoScan and click sharing. You can assign a name to the device. Go to other networked computer and add the device. You should be given an option to locate device on a network. Install the same driver and software you want to use with scanner.

Note: I'm not a Mac user, I've given instructions based on Windows XP/Vista. But, process should be similar.