Put the summary of the bug you're having here

What I expected to happen was...:
Redstone feedback to the quantity of items on the stack. (e.g. A stack of 32/64 items lights up 8 redstone dusts)

What actually happened was...:
Counts the number of unique items on the plate, a stack is an item, drop more and it increases the signal length then comes back to one, add a different item and adds on the signal.

Steps to Reproduce:
1. Place a Gold pressure plate and a line of 16 redstone dust.
2. drop from above some stackable items. observe.
3. drop some more same items and observe.
4. drop some different items.