If the golf ball you are using has two digits, this is not as much to do with being able to identify it but has more to do with the compression rating.
Of course, you could still use this number to identify the ball if nobody else you are playing with has the same.
The compression rating refers to the feel of the ball and balls that have lower compression, perhaps around the 70 or 80 mark would typically be a ladies’ ball.
On the other hand those with a higher swing speed might need a ball with higher compression.
While these numbers did used to appear on golf balls quite frequently back in the 1990s, it isn’t quite as common nowadays.