A clerk or transcriptionist can easily spell something in the way they are used to–even if the word is not supposed to be spelled that way.
I have two ancestors whose last name is Bieger. I’ve typed the name more times that I can remember.
Recently I had cause to mention the singer Justin Bieber in a comment on Facebook. It took me four times to spell his last name as “Bieber” instead of “Bieger.” I wanted to spell the name the way I was use to spelling names that started with “Bie” and ended in “r.”
Is it possible that a clerk’s “mistake” was simply a habit that they applied to your relatives name when they should not have?