In People v. Dixon, 23 Ill. 2d 136, 137, 177 N.E.2d 206 (1961), the supreme court determined the exception to the rule requiring a showing of prejudice applies where it "would be impossible or inordinately difficult to make a showing of prejudice, for it can not be shown how the testimony might have differed had the motion to exclude been allowed." Dixon, 23 Ill. 2d at 140. In Dixon, the trial judge denied the defendant's motion to exclude witnesses based solely on his practice to the contrary: " 'Well, I don't like to do that.' " Dixon, 23 Ill. 2d at 137. While the supreme court ultimately determined that it remains within the trial court's discretion whether to grant such a motion, "a motion to exclude witnesses should normally be allowed." Dixon, 23 Ill. 2d at 140. "In order to uphold the denial of a motion to exclude, the record should disclose a sound basis for such denial. Where the record discloses an arbitrary denial of a motion to exclude witnesses, it is not necessary for the defendant to establish that he has been prejudiced thereby." Dixon, 23 Ill. 2d at 140.