Midi File import creating multiple parts from monophonic input - again

I tried updating a previous post about this, but that seems to result in no replies, so I'm creating a new topic repeating an old problem...

Original thread: https://musescore.org/en/node/374262

Basically, Musescore is splitting what I think is a monophonic midi file into two parts. I am running into this problem again. I've included what I see when I open the midi file, and the midi file itself. I checked very carefully for any overlapping notes, even used a feature in Logic Pro which ensure overlapping notes. It's a monophonic part. Yet it gets split into two separate parts on import.

How can I figure out what is going on here?

Also, when I use "Implode" to try to merge the content, I get these funny markers I can't remove. What is that, and is there another way to easily merge the parts onto one staff?