What you are describing is setting up the Live Set with two "copies" of the SAME performance. They're not really copies like we think of files in a computer. In computer terms, it's more like a symbolic link. Where both "copies" are really pointing to the same thing. This is why modifying the performance changes both with your modifications.

In Windows terms - you can think of the Live Set slots as shortcuts to performances. None of the slots store the performance. So when you see "copy" - this is not copying a performance. Instead, it's copying a shortcut to a performance. In Windows we know we can have multiple copies of a shortcut and modifying the original file which the shortcut is referencing will update the file which all shortcuts (to the same file) point to. When we copy a shortcut - we do not say we are copying the file. We say we are copying the shortcut and know this is not the same as copying the file. Therefore your language of "copying a performance" is not exactly accurate.

In the context of a live set, you can think of your "performance" in the live set as a "voice" in Motif. Not literally, but more in terms of function as an editable entity. In Montage when you place a performance in the live set - this is like in the Motif placing a voice in a performance. You can place the same voice in multiple performances (of the Motif) - and each performance in the Motif which shares the same Voice - I don't think you consider this a "copy" - it just IS that voice in multiple places. So if you go back to voice mode and edit the voice, then the voice edit changes all the performances which use that voice.

Same deal with the live set - this is just sticking the same performance in multiple slots. If you change the performance ([STORE] an update) then that update will be replicated across all live set slots that use the same performance. One parameter - like "output level" is something that can be set at the "live set" level and therefore, this overrides (for each live set slot) the output level of the performance. .... therefore changing the "output level" of a performance may not necessarily change the live set slot's level - but this is more of an exception.

So if you wanted in the Motif to have the same kind of voice - but not have edits change ALL your performances - you would create a USR (user) voice based off the original voice. I think there's a job copy voice to USR function. Been a while. At any rate - you'd make a new voice that's based off the original voice and make your edits to this new voice. And then add this new user voice to your performances that you do not want to "tie together" to the original voice.

The concept is the same here - what you would do is go to the performance you want to edit and make different. Press [PERFORMANCE] (HOME) to get to the "home" screen, then press [STORE] to save user COPY of your current performance (before making your changes) - you will be prompted to overwrite or create a new performance (with custom name) - choose to create a new performance and name it how you want. Then make the edits on this copy-of-a-performance. Be sure to [STORE] the edits - you can overwrite this time since you've already made a new performance. Last, in live-set, you can ADD this new performance to the list. Editing the first performance (since it's a different one altogether) will not update the second one.

The quick primer:
a) If you want two different performances in live set slots, don't copy them in live-set mode
instead ...
b) Go back to [PERFORMANCE] (HOME) mode and [STORE] (do not overwrite) a duplicate of the original performance
c) Make edits, [STORE] this duplicate with edits (can overwrite this time)
d) Go back to live set mode and add the newly created duplicate

I really kinda already knew to do that - in this age of button pushing I guess I was just looking for a single
button that would do it and let me save a new name to it. That's actually pretty freakin' lazy now that
I think about it. Damn.

I totally get everything you said though. And yes - I've made many edits of a standard preset voices in
the ES to use in different performances in the past - sometimes 3 or 4 saved edits of the same sound
with a minor tweak here and there - each one for a different performance.

That's pretty much the same thing I always do with any Word or Excel document I make. Take the
original, do a "Save as", change the name and you're done. You have an exact copy that you
can mess with without ruining the original.

Oh well - sorry for being lazy.

No problem. It does take some time to get oriented. I think you're doing a fair amount of work to make it to Live Set details as your first question.

Thanks. I feel pretty good with the progress I made in such a short time - kind of surprised me that I got it so quickly.

Those familiar with previous generations, as you are, will find there are more parallels than completely new concepts with Montage vs. Motif or MO. Some of my initial work was also, as you seemed to do with the ES, mapping out each screen on the previous Yamaha keyboard and Montage - forming a spreadsheet of what screen/parameter on the previous keyboard mapped to Montage's screens. Although organized slightly differently, all parameters were pretty much 1:1 between the old hardware and new hardware. In that sense, I liked that Montage didn't throw out legacy and create something completely revolutionary because it meant I could manually convert performances which are not automatically converted.

My keyboard was also part of the "ES" series (the MO6 - which is the same generation as ES). It's very beneficial that work done on keyboards several generations ago still can carry forward and should give some sense of comfort that legacy will most likely be considered the next time you elect to upgrade within Yamaha's future flagship offerings.