Fell down my mine, died due to fall damage, had to exit the game once I got to my items. Came back, noticed everything in my inventory was duplicated.

So I accidentally fell into my mine which goes almost all the way down to bedrock. I hit the ground and obviously died of fall damage. I ran back to my stuff and had to leave the game due to personal reasons. When I got back, I noticed that my stuff wouldn't fit in my inventory. So I picked up 2 of my leggings and noticed they had the exact same durability. I then looked at everything in my inventory and noticed that everything had been duplicated. All of it was real items and not fake items that wouldn't do anything.