Humor me if this a bit of repeat topic or discussion, but… are there any plans by the developers to allow for duplicate costumes to be recycled like the Goblin Crates or possibly transmuted via an “11th level” for the Alchemy Lab? Have over 20 duplicate 4-star & 3-star costumes, and it would be nice at the very least to swap for costumes for heroes currently held.
You can “feed” the duplicate costumes away for vast Exp & Special Skill increases:
Note you can only feed duplicate costumes to the costume version of a hero. Accessed in the “level up” screen by changing the tab from “heroes” to “costumes”
To answer the OP, the answer is No. Nothing on the horizon has been added to, tested in or hinted at in beta.
They are best used to fast level the costume version of any hero.