What is the most common rugby score?

Answer 1

1-0 followed by 1-1, the home team is most likely to win with scores 1-0, 2-0 and 2-1 in that order.

Answer 2

In my experience a converted try with either 2, 3 or 4 penalties is probably most common. So that's 13, 16 or 19 points although higher scores are often reached.