Duplication in crafting bench

I only tested this using Redstone torches. When I made Redstone torches and had enough Redstone not enough sticks, first I crafted with enough items, and then when I was out of sticks it gave me a view with a red blocked stick and a normal grey block of Redstone. Then I manually placed a Redstone dust in the crafting table, over the other dust. it then put 2 in there, which duplicated the Redstone dust. I was able to duplicate it.