With my Keystep 37 I can send MIDI to a hardware synth (using a MIDI cable) while also being connected and sending MIDI to a computer through usb. Can the Keylab 88 mk2 do this as well? My Native Instruments S88 cannot do this.
Given both MIDI and USB are sending controller data, it does't make sense per standard.
This is like some saying "Can I open a door by also closing it?"
However, based on what I have seen, it should work if the application you are using supports it.
Just to put this in context, when I connect my Korg Kronos 2 to certain software, I have to specify what interface/connectivity I am using, so in a nutshell I cannot use both.
I cannot say, connect to track 1 using USB and Track 2 Using MIDI.
If you are attempting to interface with a device/software which allows multiple connectivity to the same device, then yes.
Again, this is unorthodox but creativity has no limits.