It’s the SC from the initial pot which you benefit from too, so you have to be careful about that.
I just stick useful stuff into pots I don’t need for example earth root the hell out of vine pots if I’m levelling my warrior.
Same goes for stacking heroic and rage, just doesn’t happen and you will waste one. Maybe a prompt messaging saying ‘A more powerful potion is already active’ could be good but I have no idea how difficult that could be and if it’s even worth investing the dev teams time into.