Has an AFL game ever ended 51-50?
Exactly once. On September 3, 1910, Richmond beat Essendon 51-50, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 51-50 in league history.
That makes 51-50 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 52-50 has happened 2 times and 51-51 has happened 1 times.