[GAMEPLAY] Viktor Chaos Storm Last Hit damage incorrect; does double damage then reduced on targets

When Chaos Storm is used, the number that is displayed for the last hit is inaccurate and far higher than what it is supposed to be for both the initial hit and the subsequent hits.

https://i.imgur.com/ttpsNiV.png

Based upon the numbers being close to the tooltips, it would appear that the target dummies' resistances are being ignored and the ability is doing its full damage. However, upon further testing, I found that is not the case. What is actually happening, which accounts for the error, is that Chaos Storm is actually doing double damage to the targets in this calculation. This is demonstrated by purchasing any of the Magic Pen items.

http://i.imgur.com/eVWZ2Ke.png

To Reproduce:

1. Start the practice tool and choose Viktor
2. Level to get Chaos Storm
3. Place a Target Dummy and use Chaos Storm on it
4. Observe that the damage for Last Hit is far higher than the actual damage dealt
5. Use the Add Gold command and buy a Magic Penetration item like Void Staff
6. Use Chaos Storm on a Target Dummy
7. Observe that the recorded damage for each of the hits exceed the amount of damage the ability can do.

This bug occurs regularly through all reproduction attempts (e.g. dozen+ times; 100% success rate). This is not caused by Runes and Masteries and testing with Mpen runes produced the expected described effect.