Powered Hopper still recives items through other Hoppers

I was experimenting with Hoppers. I put a Hopper(1) above another Hopper(2). When Hopper(2) was powered, it still received items from Hopper(1).

What I expected to happen was...:
When Hopper(2) was powered, it wouldn't receive items from Hopper(1).

What actually happened was...:
Hopper(2) still received items from Hopper(1), even though Hopper(2) it was powered

Steps to Reproduce:
1. Place a Hopper(a).
2. Place another Hopper(b) above the first one.
3. Power the Hopper(a)
4. Hopper(a) still receives items from Hopper(b).