S.C. Code § 7-13-1130
If ballots shall be found on opening the box, upon which shall appear the name of an office or the name of a person in connection with an office other than that for which the box in which such ballot is found shall be designated and labeled, these ballots shall be counted, if in counting the ballots for that office the number of ballots does not exceed the number of names on the poll list. If the number of names on the poll list is exceeded by counting all of the ballots, then none of the ballots for that office found in the incorrect box shall be counted. If, in counting, two or more like ballots shall be found folded together compactly, one shall be counted. The other shall be destroyed. But if they bear different names, all shall be destroyed and none counted.
S.C. Code § 7-13-1130