I just updated my Poser version from 13.3.686 to 837.  In the release notes under version 13.3.824, it says:

- Completed feature request - create flipped morph (App) #1813 (Beta) #211

Yes, that appears to be what it does. Odd choice of naming 'flipped' instead of mirror.

It's not a mirror. We already do that. A mirror is the same on both sides. Flipped will swap both sides.

So

If the character has raised an eyebrow when mirrored the figure raises both eye brows

When flipped only the opposite eyebrow is raised.

The smirk swaps sides, the JCM for the other side of the figure.

Yes this is really, mostly for people creating  content. Making a JCM is a big enough pain making one. But, making a symmetrical JCM for the opposite side was nearly impossible. Was. Now you can just flip it.

I'm supposed to have already done a tutorial for this but I keep getting distracted. Stay tuned. There's some limitations and clean up necessary once the flipped morph in created. I'll cover all that.,

Thanks, nerd. Sounds terrific! I'm always using the morph tool and use mirror all the time. Flipped seems very useful, too.

Ok so it makes a mirrored copy of the morph, which eliminates the step of having to split a mirrored morph into L and R.

How much more difficult would it be to mirror the linking setup along with it (if it exists when you create the mirror)? Because that would definitely be a time saver.

Nerd, will the tutorial be here? Or an update to the manual? Or a product for purchase?

It's the answer to my years-long prayers, it's what that is. LMAO