Cheats: I have only discovered one cheat for this version of the game. If you have more, feel free to put it on here.
Duplicating: this only works on blocks, but having an extra six coal blocks never hurts.
Okay, so, get the appointed block and go outside and put it down.
Simple, right? :-)
Now, save. (Open settings, click exit, click save) once you have saved, mine the block. Now quit without using the exit button. (Click home, shut down, anything works, as long as you don't use the exit button) now do something else for a while then come back. (Has to be a different game) now go back and get on the same world. You should have the block in front of you and the same block in your inventory. Now you have 2. :-)