I am trying what you said to get it dupped but i cant seem to get it, do you have any other method of an idea of why this may happen?? so i can look into fixing it?

I don't know how old this thread is but I had a question. I am trying to do the dup glitch, the one where you alt f4 the game and I am having a hard time. When I crash the game and go back on the world I end up where I was before I went in to pick up the items. In other words, I am not standing on where the items are and I am not duping anything. I have looked up many videos and I cant seem to find out why this is the case. I even reverted back to the old launcher just to see and still the same thing. I am trying on 1.8.3 I have tried on 1.8 and I even made a micro to see if I just wasn't doing it fast enough. If anyone knows what the deal is then please tell meh.