I have a theory what happened there. Lets say the right wing has 100 damage points before it fails. An ally shot up the right wing down to 20 damage points. Lets say he then crashed or got shot down. Then, LosSuns came in and hit him with a few beebees and brought damage points down to 9. You then came in and finished off the wing with destructive force, but only got credit for the final 9. Since the ally tallied 80 hit points but got killed before the spit died, LosSuns became the primary damage holder with 11 points compared to your 9 points. Pretty rare scenario but that's the best way I can think of of what happened.
All that being said, I think there should be a small damage bonus rewarded to the player that inflicts the fatal shot. Such a bonus would swing close damage scores to the player who actually took down the bad guy. "What" that damage bonus would be, whether it be 5%, or 10%, or 15%, that would have to be decided by the higher ups.