If you ordered a certain flavor, and you had the option to add 2X's the flavor, does that hurt the quality of the e-juice?
It depends on the supplier. A good supplier won't dilute the nic when adding extra flavor. Also, "2x" doesn't necessarily imply you're getting twice the amount of flavoring. Some juice makers on some flavors will only go to like 125% rather than 200%. But however they do it, the nic level should stay the same as they'll use a stronger base per calculations.
I love double or extra flavoring in my juice, ya gotta be careful because each mixture of liquid has its max with flavoring that ou can add before it destroys the juice mix, but I love to taste my flavors in my vape. I think it is also very subjective, some people like a light flavor some medium and some heavy, I'm on the heavy side of it and love to be able to really taste my flavors in my vape, although it also depends on the flavor, some flavors don't need it at all then again for some it's a must.!!!