How to Comp 2 lines

That would be what I would do so both original comp tracks would be available but you create one comp one, bounce it, then create a different comp from the original track and bounce it. The problem with this approach is the original comp track is lost.

I often track vocals using more than one mic ... first of all to have a choice/backup later when mixing so I can select the one that sits better in the mix ... BTW, I use auto-grouping so general edits are applied to all vocal tracks from different mics ...
 
Which gives me "cloned" tracks, but from different sources (different sonic character) ... so for double tracking I can go with the same or the alternative mic(s) i.e. not the first choice, which sometimes is an advantage - because with very similar takes from the same microphone you may get phase issues ... Now, with Vocal Sync it's become a lot easier to make the takes VERY similar ... which is good, but may have side effects ...

Squirebum, that is some good information right there that I could have used this weekend. I assumed when I flattened the comp that that was it ,never tried to mute the comp. Thanks for sharing that tidbit.

I didn't know that either and is exactly what I'm looking for.
 
Good work Squirebum

SquireBum
You may already know this, but you could use Flatten Comp multiple times on the same track without the need to clone the track.  If you select Flatten Comp and click Mute on the new Comp take lane, Sonar clears the Mute button on all of your original take lanes so you can create new take selections for another Comp.  I could not find documentation of this feature, but it works for multiple comps and you can work on a single track.

This is how I would do it then either within the same track or in a clone after the first comp is completed.
 
This way all your slices are already there and you just use speedcomp mode to change the takes being used for the second one. The best way to go about that is to make sure you put notes on the takes. Make sure you label your first comp as Comp 1 so you don't reuse anything by mistake. As long as you are doing the first comp you can label potential candidates for comp 2 to speed up the process (that way you don't have to listen to everything again).
 
There are two main scenarios I would do this with.
 
One would be to have two (or more) good comps (basically weeding out all the bad parts). That way I can do a final comp between those two or three without getting distracted by the reams of other takes I've already weeded out. Kind of like sifting out the bad stuff first then doing the final. You need to unlock those comps first though. Also might be helpful to clone the track before beginning the second pass comp so you are only looking at two or three take lanes insteead of a huge pile. Then Archive and hide the track you recorded into to get it out of the way.
 
The second of course is doubling in which case you definitely want to clone so that you can audition things in comparison with your first comp to get better matches. You will also be able to pan the two parts to get a better idea of how it's going to sound in a proper mix (like doubled guitars). You of course may also want to change where the slides are and/or adjust your crossfades. By cloning your first comp's slices are preserved just in case you want to go back. If you did the method of creating the "pre-comp" comps using only the good stuff you could clone that version (instead of the original) so you are looking at less take lanes.
 
So in the end after you've done your precomping you have two identical pools of good takes to work with and you can easily match things without a bunch of scrolling around between tracks.
 
Short version...
 
1) Do your tracking into on track getting a massive pile of takes.
2) Go through and make time based notes in the take lanes notes section (00:00-00:45 good, 00:46-01:30 don't use, etc)
3) Making your comping splits with the Comp Tool wherever appropriate
4) Create a bunch of comps and maybe include notes to say which sections of each comp used which takes (I use the take lane numbers for that... so 00:00-00:45 = T1, 00:46-01:30 = T2, etc). That way later on you can avoid using the same performance twice. 
5) Clone the track once, in the clone delete all lanes except the flattened comps, unlock the flattened comp clips.
6) Clone THAT track and archive/hide the original track
7) Create your final comps using the two cloned tracks
 
Cheers.