Battlefield 3 WTF Moment (Knife Trading)

I was playing tdm on noshahr canals and I went up to knife the guy in the video. We traded knifes and I was wildly confused. I don't know if he was hacking or not but if he wasn't then DICE fix your game. Even if he wasn't hacking fix it please haha.

EQUIPMENT AND SPECS:
1000gb, 8g ram, amd processor.

BATTLELOG PAGE AND PLATOON:

[oknu]

when someone with less than 50% health knifes you, you can quickly press "F" to knife him back. that bug was propably fixed on Aftermath update.