In PM+ Beta 4 on a Mac 10.14.5
When I perform a Save as on an image that has the NEF and the JPG combined, PM creates 2 new JPGs, one from the NEF and one from the JPG. This is different behavior that before. I formerly just created one JPG, based on the selected Save as settings, applied to the original JPG.
Attached is a screen shot of my Save as settings.
I am not rendering raw images, as when I have that option set in PM, the Adobe DNG converted continually opens and closes in eh background while PM is running, eating up my laptop battery life, if I am mobile.