I have someone in my tree who had four children with his wife, Anne McKenzie (b1828). When she died he married Ann McKenzie (b1838) and had five more children with her. It certainly caused me some head scratching until I worked it all out!
My great-great-grandfather married Agnes Collingwood and had 3 children together. She then died aged 31. He went on to marry her first cousin Agnes Cockbaine. They were both named after their grandmother.
If seen a case here in Ontario, Canada where there were two Seth Laraby's -- both married to women named Esther. Though they lived 100 miles apart, a number of researchers kept intermixing the information about the two families -- probably because they "cut and pasted" information from one site to another with checking the original records.