Notwithstanding the provisions of Article 493, offenses in which punishment is necessarily confinement at hard labor may be charged in the same indictment or information with offenses in which the punishment may be confinement at hard labor, provided that the joined offenses are of the same or similar character or are based on the same act or transaction or on two or more acts or transactions connected together or constituting parts of a common scheme or plan. Cases so joined shall be tried by a jury composed of twelve jurors, ten of whom must concur to render a verdict.