In Pro Tools, go to Setup>Midi>Midi Studio. In that menu, create new "instruments" for both the Motif and the Roland. The brand and model settings don't matter, but the setting that REALLY matters is the Input Path. That setting needs to be set for each keyboard, according to how the keyboard connects. Once both are properly configured in that menu, close that and create 2 stereo instrument tracks(for testing). Stick MiniGrand on the first track and DB-33 on the second and put both tracks in Record-ready. Playing either keyboard SHOULD play BOTH instruments. Hopefully, they do(and this is because Midi/Instrument tracks default to receiving from ALL midi sources).
Now open the VIEW menu>Mix Window and check "Instruments". That will open a row across the top of the MIX window showing midi assignments. In those boxes, you can set each track to receive from ONE of the two keyboards. You also have the option of setting individual MIDI channels if needed
Hope it works
