I seem to be having issues with blocks duplicating with in blocks.
As I go into a block to edit it the original objects are there to edit but it also shows there is a duplicated version of the the same block with in it. If I delete the duplicated block leaving the original objects when I exit the block it deletes the whole thing and I can then to recover it by using undo. Im not sure if it have something to do with it not working in the original file the block was made in as I have saved a back up copy etc. or if it has something to do with the objects in the block being on different layers.