So, lets say someone didn't bother to read the blog post that covers the record options for multi-track grouping and went ahead and recorded multiple takes of an acoustic guitar in a recording session on two tracks, the two tracks being for a mic and the piezo pickup.
 
With the intention of comp'ing the takes of both tracks simultaneously, how can this recently enlightened user recover from this mistake?.. (the hypothetical subject of this post you understand, and not representing anyone living, dead and specifically not representing someone sitting at his desk in Mystic right at this moment, for example) ..
 
Can this be done by grouping the tracks? other ways?.. thx
 

This hypothetical user sounds a lot like me!  Yes you can recover. Just CNTRL click each clip you want to be grouped to select them all (e.g., mic take 1 and piezo take 1).  Then right click on one and select "create group from selection" (or something like that).  Do that for each take and you are good to go with comping.