User blog comment:SpiritedDreaming/RWBY: Attack on Kevin Tower Defense Game/@comment-26397825-20161012121231/@comment-26397825-20161012124837

Here is the comment chain where the double damage thing was first suggested.

And here is the date it was implemented.

You don't have to spread the damage out. What it does is makes the maths easier on me, and means that if something only has 3HP left, you don't have to waste that 4th piece of damage you can do. You can instead shift it to another target. Or you can do 3 points of damage to one creature and 1 point of healing. Or however you'd like to use it.