If you drop a stack of items onto the petal apothecary, it will contain one extra item of that type. You can then remove the items, which means you get one for free. This only occurs if you're standing on the ground next to the apothecary and drop a stack that's greater than one item in size so that it lands on the apothecary instantly.
I think this is due to an interaction with Realistic Item Drops. The apothecary is catching the original item before it's converted into a "realistic" item.
If you drop a stack of items onto the petal apothecary, it will contain one extra item of that type. You can then remove the items, which means you get one for free. This only occurs if you're standing on the ground next to the apothecary and drop a stack that's greater than one item in size so that it lands on the apothecary instantly. I think this is due to an interaction with Realistic Item Drops. The apothecary is catching the original item before it's converted into a "realistic" item.