Here's the update if anybody still cares:

- all notes are MIDI-channel 1
- I turned off some random stuff in MIDI options of the keyboard, so now it records not triple notes, only double
- I haven't layered the sounds, it happens with every single instrument, God knows what happens with programs, I haven't even tried
- there is no significant other MIDI option in the sequencer apart from MIDI THRU, no echo mode


thanks guys