There is no facility to copy tracks.

That would be considered an advanced sequencer feature - which the Performance Recorder does not support. You'll need to save the MIDI file to a USB stick and use a computer to change the track then re-load into Montage. Not possible on Montage itself. Either that, or re-record and start with the intended track.

One "trick" I use when I work DAWless, is to take a recorded midi sequence, and set it to a drum type arp for all parts, so that it plays back exactly what I or the arp played. This works great for taking a tune and breaking it up into scenes where there is a scene for verse, chorus, bridge, etc. You can play along as you work on an arrangement, plus you can jam along on 2nd keyboard. Using the arps this way, you could easily assign the same arp to multiple parts. This user arp assignment workflow is alot easier than it sounds and is great for capturing ideas, carving out sections of a jam for an arrangement, and then using the scenes like the ol sequencer on my MO6 with the a-h parts. Takes me like 2 minutes to get 4 scenes with 4 or so parts each setup. Worth trying this "trick" as it works just like patterns and is just as easy to setup on the fly, once you do it once.

Just so there's no confusion for other readers - Mitchell is referring to the "Fixed" type of ARP. Commonly used for drums since drums are in fixed piano-key locations and you typically do not want to "transpose" a drum pattern up and down the keyboard. The combination of kit pieces would be perhaps nonsense if moved. Fixed can also be used when you want a musical phrase to exist only on the original played notes. This style of ARP for non-drum PARTs is as close to pressing "record" on a tape recorder as any ARP type available. No matter where you trigger the ARP, the notes will come out as originally played. No chord recognition, no transposition.

What Mitchell is not saying is that all PARTs have drum sounds.

Thought I'd clarify.