XP is being duplicated?

The Hello Kitty My Dream Store dungeon is currently open. There's a 'Watch Ad' mission within the dungeon. If you watch an ad while purchasing energy, you'll complete both the dungeon mission and the 'Watch Ad' hidden quest. Completing the hidden quest grants 15,000 XP and Party Points. As a bonus, you get 150 gems from the dungeon mission rewards and the hidden quest rewards. However, the cooldown for the 'Watch Ad' dungeon mission is only 1 minute. And I'm not sure if there's a limit, but every time I watch an ad, the 'Watch Ad' hidden quest gets completed. This means...