In any trial the court need not reject any witness against whom it is objected that he has, without the permission of the court, and without the consent of the party objecting, been present in court during the proceedings; but the court may, in its discretion, admit the witness, where it appears to the court that the presence of the witness was not the result of culpable negligence or criminal intent, and that the witness has not been unduly instructed or influenced by what took place during his presence, or that injustice will not be done by his examination.