Has an AFL game ever ended 51-51?
Exactly once. On May 27, 1922, Fitzroy and Essendon drew 51-51, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 51-51 in league history.
That makes 51-51 the 3884th most common final score out of 6,649 that have ever occurred in AFL. One point away, 52-51 has happened 7 times and 51-52 has happened never.