lol... why is that something i could see Snape doing with the points? ^_^

That is a very interesting question! The only answer I can come up with right now is that there would be a sort of mental struggle between the summoning parties. I envision it as a 'tug-of-war' between the minds, really. The person whose focus and concentration on the object (and perhaps even desire for the object would play into it) is the strongest and most intense would be able to summons the object in the end.