Milking mooshrooms in creative mode grants mushroom stew even if it's already present in your inventory

The Bug:

Milking mooshrooms in creative mode grants mushroom stew even if it's already present in your inventory.

Steps to Reproduce:

1. Switch into creative mode and summon a mooshroom.
2. Obtain a bowl and use it to milk the mooshroom.
3. Take note as to whether or not you have some mushroom stew in your inventory.
4. Milk the mooshroom again.
5. Take note as to whether or not milking mooshrooms in creative mode grants mushroom stew even if it's already present in your inventory.

Observed Behavior:

You are granted mushroom stew even if it's already present in your inventory.

Expected Behavior:

You would not be granted mushroom stew if it's already present in your inventory.