The way I use both keyboards (Keylab essential 49 and Keystep 32) is that I might want to use a lower octave for some bass using the keystep 32 and then add some organ at higher octaves. This way, I don't have to press the OCT+ or OCT- each time. This gives me the ability of having a virtual 81 key keyboard.
You could set one keyboard to one midi channel such as CH1 and another to a second channel like CH2 which would isolate each keyboard. This is a good thing if you want to create a multi-instrument where instrument 1 is controlled by keyboard using channel 1 and instrument 2 controlled by keyboard using channel 2. To do this
1- click on the ANALOG LAB logo in the top left corner
2- click on NEW PRESET
3- Drag the first instrument (I chose "Caspian" as an example which is a SEM instrument) to PART 1 (or click on PART 1 and select the instrument after,
4- Drag the next instrument (I chose "Bolero chord lead" as an example with is a MODULAR instrument) to PART 2
5- Click on MIXER at the top right under STORE
6- Click on MIDI SETTINGS - You'll see the range for a split multi instrument
7- Select the octave range for instrument 1 which is normally C-2 to G8, change the G8 to B1 (as an example)
8- Select the octave range for instrument 2 which is also C-2 to G8 and change the C-2 to C2 (which is above the first instrument
This way, keyboard one controls one instrument of the multi instrument preset you created and keyboard two controls the other.
To finish the preset, click on the SAVE AS... button then SAVE AS MULTI, enter the name you want, the bank, your name as the author, select the template or enter your own name, click on the styles it represents, fill in any comments then click on the SAVE button.
You can always make changes later on as needed, even change the octave range of the keyboards etc etc etc.
Hope this helps.
