I've always shot jpg and RAW. Just recently, LR started to show both files for every photo. I only want to view RAW. In preferences/general - "Treat JPEG files next to raw files as separate photos" is unchecked but I still see both files next to each other in grid view.
I would choose to treat the RAW and JPEG as separate files, but, if I did import the JPEG, I would place them in a separate folder.
Note, I shoot RAW + JPEG, but, I keep them on separate SD cards when shooting, and I shoot RAW + JPEG, only so I can Pixal peep the full JPEG instead of the itty bitty JPEG embedded in the RAW. Rarely actually import the JPEG.