Igloo basements generating a brewing stand and flower pot can duplicate the item held upon generation

Somehow the igloo basement duplicates its items in the brewing stand and flower pot. It is weird and kind of an awesome bug if you want to keep a weakness potion for the 'zombie doctor' achievement.

How to reproduce:
1. type in the command /locate igloo
2. teleport to the igloo
3. go down the basement
the item duplicates where the flower pot and the brewing stand is
Note: the located igloo does not always guarantee an igloo basement. A seed that always guarantee a igloo basement is:
42

Credit to WRSomsky for the seed