No Roland, you misunderstand, I think...
Because of the relatively narrow exposure range of exposure latitude of chromes, taking a bracketed series of exposures while copying the slide allows one to regain the range captured more realistically. I am struggling to explain it (I am not good on this technical exposure stuff) but shadow detail requires a long exposure to 'see' the shadow detail, the nicely exposed areas respond as expected but the bright areas, like sky and brightly lit parts of the original need much shorter exposures to help recover the details there.
I began to realise this when I was copying some of my fathers slides taken with a Zeiss Contaflex, with no meter and working by guesswork he had quite a few slides which he had rejected but kept in a separate box, I worked through these first, working on the assumption that I would develop my technique with the difficult ones, the better exposed ones would be a doddle.
On some slides I had to feel my way using a wide series of manual exposures to finding an optimum exposure for the slide. Examining the exposures in the computer, I began to realise that the longer exposures were revealing (hitherto) invisible shadow detail and the shorter exposures were revealing much better detail in the bright areas, allowing texture and shades to be shown which didn't appear in the mid range exposures. By combining some of the longer, middle and shorter exposures in the Lightroom HDR process, I was able to create a single, very acceptable image from a slide with poor shadow detail and relatively blown out sky. I tend to make quite a few bracketed exposures and choose just some of them for the HDR set, deleting the ones where no advantage is seen. I have also found turning down my illuminating light helps reveal a better range in the bright areas but poor colour saturation eventually calls a halt there.
Hope that makes it clearer, I still don't completely understasnd it. LOL
Edited for clarity.