I assume you are talking about the difference between the number of dice displayed in a roll template vs the number of graphic dice rolled on the tabletop. Many systems require extra dice to be rolled in certain conditions (advantage, critical hits). All dice must be rolled at the time of rolling. The dice engine does not have discretionary logic; it doesn't"know" when extra dice are needed, so it rolls them all. The Roll Template only shows dice that are needed; it does have logic. So unless there is a crit, it will hide the extra dice. The graphic dice engine is not connected to the Roll Template. It just rolls every die required and displays them. So if you are rolling 3d6, but on a crit you would roll 6d6, the roll template displays the first three, but the graphic dice display all six. In practice, the graphic dice are more of a fun thing to watch. For the official roll, always consult the chat window.