Some may be lawfully married to their first wife. Common law if nothing else. Some of those first wives are shown as in their 40s and even 50s.
Besides, I said "shown as", meaning on the Bishops' lists, where they are shown as "wife" under "relationship". Except one old boy (younger than me though) apparently turned that around and wrote "husband" and "father" where appropriate, rather than "wife" and "son"/"daughter". But I guess that is his relationship to the persons listed. :)