When a defendant is charged with a single criminal offence but the evidence suggests more than one discrete crime, what is the law on unanimous agreement?

When a defendant is charged with a single criminal offense, but the evidence suggests more than one discrete crime, all the jurors must agree the defendant committed the same act. If the prosecution does not elect to rely upon a single criminal act, then the trial court has a sua sponte duty to instruct the jury it must unanimously agree the defendant committed the same specific act. (People v. Russo, supra, 25 Cal.4th at p. 1132.) This requirement " 'is intended to eliminate the danger that the defendant will be convicted even though there is no single offense which all the jurors agree the defendant committed.' " (Ibid.)