I have re-checked the handwriting on the Iowa records, with the benefit of your comments.For the first marriage, the best translation is Hatsner.For the second, I'll stick with Hatchner.
Although I don't have all the facts, possible scenarios for Mary's dual surname could be:
1. Mary was born to Mrs Hetsner before her marriage to Mr Hetsner i.e. child of a previous marriage. 2. Mary was a child of an unmarried Hestner daughter, but used her father's surname on official documents. 3. Mary was adopted or fostered by the Hetsners.
Either way, she was apparently known as a Hetsner, but her legal name was Scheeman - a fact apparently not known to her son when he was married.
By the way, the second marriage Licence No. in my previous posting should be 1605, not 605.