Exporting a song with multiple drum channels to MIDI doesn't work properly

[Dogo6647]

The first drum channel works fine, but the other ones get converted to "tink" noises. Is this a MIDI limitation or is it an actual bug from beepbox? Here's an example of an affected midi file:
mid-full.zip

[johnnesky]

Yeah that's a MIDI limitation. MIDI allows up to 16 channels, exactly one of which can be a drum set channel.