grenv: We can only speculate about the cause of the problem, since we didn't write the code.

If we are to speculate, one possible hypothesis could be that some unintended event prevents the dice from being generated in the normal way. Whenever this event happens, you get the same dice as the previous roll. When it doesn't happen, you get a random roll. We must assume that this hypothetical event would be something that happens at the second player's first roll - but again, this observation is only useful to someone who has access to the code.

As an aside, if this hypothesis is correct, the event seems to happen in roughly 1 out of 3 games.