by clivej
I'd say it doesn't establish a precedent, and Character Upgrades are the only thing you can stack up and replace like that.In particular, we know authoritatively that you can't stack Relationships. And it's very clear you can't stack Scars (you wish!).
I'd also say that a card with two stickers on it is a card with two stickers on it, even if one is on top of the other.