Tear of the Goddess loses stacks when undone in shop

When i was playing Cass in ranked, I had a tear. I had 500 stacks on it. Then I accidentally bought another tear and then when I clicked undo, it would undo the 1st tear I had and not the 2nd one i had. So I had to sell the new one with 0 stacks just to get rid of it instead of undoing it. And I would have to buy the tear again just to get the tear back with the 500 stacks.

First I just had the tear. Then i bought another, then tried to undo it and then it would undo my current tear with stacks. So then when I buy the tear again the tear I had stacks on came back. Then I would have to sell the one without any stacks to get rid of it instead of undoing it.