Dice Collectors,

A question has come up about casino dice and your expert opinions are needed. Thanks.

1) On some casino dice, there is a number printed on them. On the example below, the number is 3137. What does this number represent? It does not appear to be a serial#, because sometimes we see the same number on a large group of dice.

2) Are dice that are the same color and that have exactly the same layout but with the a different #, considered to be different for collectible purposes? Meaning, do you collect dice that identical, except for the #?