Has an AFL game ever ended 101-51?
Exactly once. On July 20, 1918, Sydney beat St Kilda 101-51, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 101-51 in league history.
That makes 101-51 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 102-51 has happened 4 times and 101-52 has happened 3 times.