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Winning the battle is certainly possible, but doing so without any losses is unlikely. The fakes have 11 attack and can take down one gargoyle with any hit. It's also strange that only 2 arrows were used. The only thing I can assume is that the battle was won with losses, but there was some kind of disconnect, and the information wasn't transmitted accurately. However, if the save files are normal, then this option is ruled out.
P.S.: No one can guarantee that a top player can't cheat. There are plenty of cases of that happening, even among us.