Hi @m.c,
when using multiple ports (or pairs) you have to give them names. I missed to write that into the documentation.
var midiInput = deviceDriver.mPorts.makeMidiInput('inp1')
var midiOutput = deviceDriver.mPorts.makeMidiOutput('out1')
var midiInput2 = deviceDriver.mPorts.makeMidiInput('inp2')
var midiOutput2 = deviceDriver.mPorts.makeMidiOutput('out2')
Hope that helps!