How to select duplicate iPhone legacy JPGs, based on set of newly imported to iPhone HEIC images?

Hi,  friends,

I  regularly import from my iPhone Photos app to Lightroom  Classic. I started  my  archive in standalone Lightroom and my iPhone  pictures go back to 2011. That's why today I set out to import all my phone  photos  and  videos,  so  I could clear  them from the phone to max out my photo space for an upcoming trip.

Unfortunately, I wound up with a lot of doubles, with LrC's import duplicating 2000+ images, in HEIC format. The  HEIC  are not only about  half the file size, I see better detail  than  in the  JPG images that  were imported years ago.

I'm tempted to want to keep  the  HEIC  in  my  archive, even though I still  get trouble  trying to use HEIC  files in 'the  real  world.' But, How  can I easily identify and select the original JPG versions  that are the doubles of  my new  imports? Before I realized the difference in  file size and  quality, I was simply selecting  and  removing the doubles manually, via Previous Import, in the Navigator. I would click  on a photo,  Go To It In The Finder, make  my comparisons, and set as Rejected any duplicates. 

But this has  been deleting the newly imported HEIC versions. Are there any ways,  besides manually, to  batch  select the  duplated JPGs, instead?