Minecraft wiki entry for Block_and_item_duplication, associated text: Items duplicated this way won't work for quick use in a recipe, though certainly can be used for Classic crafting and any other use. However, if you wish to revert an item to the default name, you can do so by crafting it into another item then crafting it back to the original (such as redstone block -> redstone dust x9 -> redstone block), or by placing it as a block then breaking it back into an item.