Gold pressure plates and Iron pressure plates only send one signal of redstone. (With the same entitie)

Gold pressure plates and Iron pressure plates doesn't work with the same entity. Only with diferent, is this a bug?

What I expected to happen was...:
In 1.6.4, as you putting one type of entittie (e.g; 18 carrots) the signal is growing if you putting more entities of the same type.

What actually happened was...:
The Gold and Iron pressure plates only send one signal of redstone with the same type of entittie, either more or less, sends the same signal. (1)

Steps to Reproduce:
1. Put in inventory a lot of any item (32 for example)
2. Drop it in the pressure (Gold, for example)
3. The signal doesn't grow, only sends 1 signal of redstone.
4. Now put in inventory one item.
5. Drop it in the pressure
6. It sends the same signal as before.