Perhaps the bridal couple lived closer to the Sang. Co. courthouse than they did the Cass Co. one, which I believe was, at that time in Beardstown (it's now in Virginia, IL). My father, age 92, and I couldn't find his Cass Co. grandparent's marriage at that courthouse, and later, when doing other research in Petersburg, at the Menard Co. CH, we found it there. This confused/intrigued my father for he didn't understand it; then, while driving home, he said, "I remember now, that the courthouse would have been clear over in Beardstown, and so it would have been closer for them to come to Petersburg." Those old roads weren't good in the first place, I'm sure, so expedience was the answer. Or at least that's my suggestion for your inquiry.