§ 76. Action for libel: evidence, separate verdicts. At the trial of any civil action for libel, the defendant may prove, for consideration by the jury in fixing the amount of the verdict, that the plaintiff has already recovered damages, or has received, or agreed to receive, compensation in respect of a libel or libels of a similar purport or effect as the libel for which such action has been brought. In consolidated actions based on libels of similar purport or effect the jury shall assess the whole amount of the plaintiff's damages in one sum, but a separate verdict shall be taken for or against each defendant and the jury shall apportion the amount of damages among the defendants against whom it found a verdict.