Interestingly, a Spanish Chronicle of 1503 reports that Juan de Merlo "conquered an important knight named Mosior de Charni" at Arras. This was almost certainly his fight against Pierre de Bauffremont, lord of Chargny at Arras in 1435.
The Burgundian chronicler Monstrelet reported the fight was a draw. He was probably biased in favor of the home team, but had much better access to eyewitness accounts than a chronicler in Spain, who would have his own bias.
It's an interesting question. What tale did Juan de Merlo tell when he returned home, and how close was it to an impartial account of what actually happened on the field?