I got killed by a blaze, respawnt and recieved my stuff back in the Nether. After that I needed to go. So I logged off. But when I returned, all of my stuff that I had dropped when I died, and that I recorved, was back. Now all the items are dubbel. So a Dublication Glitch.
Please force a crash report by holding F3 and C for 10 seconds and attach it. Please also include steps to reproduce the issue.