The rules state that the dice will not show pieces that are no longer on the board, there's no mention of only showing pieces that can move. I can imagine game states where a piece might not be able to move initially but could if other pieces are moved first although I suspect it would be difficult to implement forced moves due to the number of options available each turn - I'm not a programmer so this might not be complicated but I have a feeling it is. It might be far simpler to show the result of all the dice regardless of their ability to be moved than it would be to calculate all possible moves and implement forced moves. In Backgammon you get to see both dices regardless of their useability.