Chest is placed down with an item inside

I am on creative and when to get a chest. I middle clicked a chest with a pickaxe in it. When I placed the chest down, it immediatly had a pickaxe in it. I midle clicked the origional chest again, and it gave me a normal chest. The two chests do not stack. The on with the pickaxe in it says '(+NBT)' instead of 'Functional Blocks, Redstone Blocks'.