In Huckleberry Finn- how do the king and duke have the money if they gave it to the sisters? ?

The give the sisters the money to gain their trust. They plan to sell the other valuables of the estate and then take back the money. A friend of the family accuses the duke and king of being imposters, but the girls won't believe him. Instead they decide to give the money back to the king and duke to invest for them as they see fit. They place the money under their mattress, and this is where Huck steals it.