I have Lightroom mobile installed on both my ipad and iphone. I also use the Apple Photos app via the cloud, so when I take a photo with my iphone, it will also be shown on my ipad.
Lightroom mobile is configured on both devices to auto import the photos from the camera roll. When I take a new photo on my iphone, I see the photos twice on Lightroom mobile (one named with the original filename and one as Copy1). On Lightroom desktop on my mac, I can see a folder named Synced Duplicates. When I delete these photos, all the duplicates will be removed on all devices.
My guess is that the duplicates are virtual copies. How can I prevent Lightroom mobile to show my photos twice (as original and virtual copy) ????
One solution would be to turn off "Auto Import" in Lightroom Mobile on either your iPad or iPhone. The photos are being duplicated across the devices using Apple Photos, so you don't need both devices to import them into Lightroom.