Hi,
I haven't actually tried it with 2 different instruments, but I did use that method with some piano pads I created a while back ie bass note of piano track1, arpeggio track2. Pads 1 to 4 on kn7 have 2 tracks, I assume your piano has the 2 tracks per pad also.
best wishes
Rikki
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best wishes
Rikki 🧸
Korg PA5X 88 note
SX900
Band in a Box 2022