The Other Duel

"They fought shoulder to shoulder yet they never, so far as is known, exchanged a single word(Borges, The Other Duel, Bohner 141)." The narrator of "The Other Duel" tells the reader about a few reasons why the protaginists of the story cannot stand each other. The narrator talks about a dispute over an unmarked cattle, relationships with a girl, and a game of cards, just to name a few.
As a reader I was questioning why, if these men hated each other so much, did they choose to be on the same side in the war and fight the same battles. I find it hard to believe that they would want to be on the same "team" as each other.
Then I thought to myself, how could these men fight next to each other day in and day out and never yell or fight or even say something to each other. Today, you see it all the time - men punching each other out over a girl, or at the very least, exchanging words. Especially since the narrator says that after Silveira and Cardoso played the game of truco, "It was then, I think, that they almost came to blows (Borges, The Other Duel, Bohner 141)." But then, I started thinking about the circumstances over why these guys hate each other so much. Is it because of the unmarked animal, card game or a girl? Sure, these things are enough to make you dislike someone but to hate them is kind of extreme.
So after reading this story a couple times, I began to question the narrators credibility. I began thinking that he is just exagerating a lot of the events in the story to make his story more enjoyable, therefore he can "flaunt" that he knows all this information and people will listen. So because I don't really believe the narrator too much, it's hard for me to try and figure out whats true and what's not.