Has an AFL game ever ended 66-31?
Exactly once. On September 1, 1906, Sydney beat Essendon 66-31, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 66-31 in league history.
That makes 66-31 the 3884th most common final score out of 6,649 that have ever occurred in AFL. One point away, 67-31 has happened 3 times and 66-32 has happened never.