To view a will from the graveyard, you click that person's name and then click the "Last Will" button. This opens their will. However, if you already have someone else's will open (from the graveyard), clicking this button will close the will, as though you're re-clicking the same "Last Will" button of the person you're currently viewing.
As seen: https://i.gyazo.com/12029acdebd1dc4dcea ... 40346b.mp4
(Technically, the new/second person's will does show for a brief moment, before closing)