I get these extra lanes that seem to be linked as well, particularly when I import via XML (sometimes there are notes, scattered in both lanes too, but it doesn’t effect the intended playback).
I just ignore them…so far things work fine.
Note, sometimes it helps in the play menu to “Load Sounds for Undefined Instruments”, reset everything in the Play tab, close out any unwanted HALion instances that might get created, and then do “Load Sounds for Undefined Instruments” a second time.