Duplicating help

[Alex890]

I am playing a game where you can equip cards. Those cards vary from rarity and i wanted to know if there is a way to duplicate them in any way. I saw this tutorial of a guy duplicating heroes in a game but i dont understand the lenguage. I would like to do like the guy in the video where he substitutes hero "A" by hero "B" to have then 2 heroes "A". Or maybe there is just a simpler way of just duping and adding cards to my inventory somehow. Here is the video link, please help me with this.