I have acquired two identical "Hard Knocks" skills. I did this after I opened a sex scene in the game where I play Diezel in normal mode and refused to completely obey by starting a cycle (this, by the way, explained to me why Mezz said that these ear clips seemed familiar to him and what incomprehensible notes he could not understand in the experimental notes, I hope that this is not true the ending, otherwise it will kill the love for this game, If there is even a concept of a true ending in this game), when I returned and I got what is shown in the screenshot. 
This time I'm sure it's a bug, because I don't see any other explanation for it being done intentionally.