I had this issue for two days. I am confident that this is a hardware issue, which is something related to the display of the LCD screen. You can either replace the LCD screen, or u wait for the phone to fix itself. For me, it fix itself, eventually. I played games along with this glitched display for like 15 minutes on high brightness (70%), then the duplicated images start to flicker in and out (duplicate flickered to normal, then duplicate, then flicker and repeat) several times and I have a normal screen now.
So I think it is a screen problem, but not sustainable as it is not supported by the system. Go ahead and play your favorite games (I was playing "Wiz, the mystic quiz"). I tried the solutions provided by others and some self-invented alternatives, like phone reset, some light knocking around the contours, re-charging, praying to God etc, but in the end, playing games does the trick.