I need help making a pickaxe that duplicates what you mined.

So I'm trying to make a pickaxe that'd spawn two of what you just mined every time you mine a block, similar to fortune but for all blocks. When I tried making it, I was able to create a pickaxe that drops its normal loot but instead of a second copy of that item, it drops the block as if it was silk-touched. Which leads to the player being able to duplicate drops infinitely. I'm using an older version of Mcreator so that I can make a 1.12.2 mod, so if you can help me for that version that'd be nice ty. :3