MIDI import - Splitting (and not splitting) tracks

I'm trying to import a MIDI piano piece where I simply have one line that's just the right hand, and one line that's just the left hand. I have 3 files, one with both, and two containing the left hand and the right hand respectively. When I import the files containing only one of the files, it splits in to two lines for some reason. When I import both at once, I can't change where the line goes so it gets all clogged up. I'd like to assume that there's an easy fix for this but I haven't found anything in the FAQs, helps, or other forum posts etc. Any replies are appreciated!