I highlight the track (for example since that's what I'm usually going for) and then Control and drag, so the original stays in it's original place and I'm only making/placing a copy in the destination track. Of course there are times when I don't need to leave the original in place, so then Control is not used, just select and then drag.
I've done this with midi drum tracks, perc tracks, and as in the earlier post, the whole arrangement, meaning all the tracks, sometimes (that's easier done another way see below), only some or maybe one.....
If you're doing an alternative mix (sounds like all the FB political stuff LOL), it's simply easier to open the project and save it with a new name. That way you have both. As Craig Anderton would advise, name it so you know which ones which! LOL Like "more acoustic" or "heavier" or "with solo and outro", etc.
Hope that helps!
Michael