Twin Cubes
Not only does a cue ball look like it has an identical counterpart inside of it, but it also looks like this dice does as well. When you crack open a dice, the very last thing you anticipate finding is another dice, which is why it is such a pleasant surprise when you do find one inside.
It is not necessary to go out and purchase a new set of dice in order to avoid throwing away the broken pair; rather, you can make do with the dice that you already have if you have any extras. If you do not have any extra dice, it is necessary to throw away the broken pair.