Persons indicted and tried jointly, for a felony, shall be allowed to strike from the panel of jurors not more than six thereof, and only such as they all agree upon shall be stricken therefrom; and if they cannot agree upon the names to be so stricken off, the prosecuting attorney shall strike therefrom a sufficient number of names to reduce the panel to twelve. If persons jointly indicted elect to be, or are, tried separately, the panel in the case of each shall be made up as provided in the third section of this article.