[Note of Caution: gives 2 marriage dates: 17/18 Apr 1768 and 17 Mar 1769 - more proof is needed.]
Both what appears to be the original register and a transcript say that they were married 17 Apr 1768 on a license from 18 Apr 1768. Presumably the original recorder mixed up the marriage date with the license date.
married 18 Apr 1768