Superior Potion Recipes in Legend Shop

I don't think you can use two of the same potion at the same time, just two different potions.

Yeah. Just two different potions. Just tried using two Advanced Int Boost Potions and it wouldn't let me.

It still says you can only use one at a time on the old potions, I'm pretty sure you can use two of the same potion of the new ones if you're an alchemist.