the duplication glitch involves the use of a dispenser and its destruction while being open. Therefore unless you can find another way to destroy a stone block (the dispenser) while interacting with it, TNT or another player are your only options. You can always use creepers, maybe get one to explode near the dispenser. But if you are around creepers you might as well kill them for the gunpowder and make TNT. Duplicate the TNT if you want to continue duplicating.
If getting hurt is your reason to not want to use TNT you can build a blast box of Obsidian to contain the explosion. If it's because you don't have gunpowder, sorry, keep searching for that elusive monster spawner and chest. It's out there somewhere.