When you are done merging tracks, the original tracks are not automatically deleted. If you recorded 4 tracks, then merged tracks 2,3,4 (these tracks green) onto track 1 (yellow), you would press record and let the song play through (completely), then, the result would be: Track 1 will have all 4 tracks mixed together. Tracks 2,3 and 4 will still be the same as they were but can now be erased if you don't need them. You can mute them (led off) and listen only to track 1 (green) and hear all 4 tracks together. Merge cannot be un-done. Just remember, any tracks that are green (play-back color) will be merged (recorded on top of) any tracks that are yellow. Only 2 tracks can be yellow at a time. Tracks that are yellow do not have to be empty in order to use them for the merge function. None of the tracks should be red unless you are recording new material at the same time you are merging tracks.