Sivir Spellshield

So I think this has been around for a while, but not 100% sure. So I noticed this in lane when I was playing mid Ahri and for some reason they had a sivir mid, but I just went along with it. So I was trying to land poke with my Q around level 5 and noticed that at max range my q didn't do any dmg. I rechecked sivir's e's description and it says "creates a magical barrier that blocks a SINGLE enemy ability cast on sivir." Ahri's Q hits 2 times so shouldn't sivir's e only block one of the times the ball hit her? It seem that her q actually blocks everything that hits it in a very small amount of time, so since I hit her with my Q at max range they both hit in a very small time frame. If you have any questions feel free to ask because I don't feel like I explained this very well.