It is not possible to obtain multiple scrolls or to buy a scroll if the player has previously unlocked the scroll's ability. When read, you get the message: The secret is yours! You unlock the ability to gain additional Dungeoneering experience in Daemonheim. There is no message for when you get Dungeoneering experience within Daemonheim for skilling. Although it is only purchasable for members, the scroll will work for non-members if they have already bought the scroll.