To reproduce:

1. Add an LB302 instrument
2. Make a simple set of notes as seen in the image attached
3. Press play
4. Try changing the bmp to get more or less errors

At some speeds it almost alternates between the two notes ... can sound a little funky :D

(I guess that the LB302 cannot really play two notes at the same time but this is hardly the desired way to handle it :)