Can I use all inputs/outputs when using Dual Unit mode with Pro Tools 9/10?

Pro Tools 9 and Pro Tools 10 only allow for the use of a maximum of 32 simultaneous inputs/outputs. For this reason if your input/output count when using two FireWire Saffires exceeds 32, you will not be able to pass audio on the inputs/outputs with a count above 32. Despite this, these inputs/outputs will show up in Pro Tools' I/O Setup.

For more information on input/output limitations see the Avid website.