To use multiple Launchpads in Max MSP please do the following:
1. Connect both Launchpads
2. Open Max
3. In Options>Midi Setup, give each Launchpad an "abbrev" setting (e.g. Launchpad 1 change to "a")
4. Use "notein a" for the main grid and scene buttons and "ctlin a" for the function buttons, where "a" is the abbrev.
5. Set the notein/ctlin objects to the appropriate Launchpad (either by double-clicking or using "midiinfo")
6. Both Launchpads will communicate on channel 1. However, it will be possible to now work with them independently.