Flower pot duplicate items if you break the half slab under that.

What I expected to happen was...:
Breaking an upside down half slab with a flower pot on it and a flower in it, should drop 1 flower, 1 pot and 1 slab if I break the slab.

What actually happened was...:
The actual drop was 1 slab, 1 pot and 2 flowers. It works with every flower or sappling.

Steps to Reproduce:
1. Put a slab in the upper slot.
2. Put a pot on it.
3. Put something in the pot.
4. Break the slab.
5. 2 flowers/ferns/mushroom/sappling.