(by Diane L Richard, Your Genealogy Today and Internet Genealogy author 6-27-2015)
Be careful of what you consider to be the “correct”, or “only”, spelling of a surname. Though we now consider the spelling of our surnames “fixed”, throughout much of history they were not. Many did not “sign” their name to documents.
Most documents were written by clerks based on what they thought they heard (I once saw a document where the clerk wrote a surname about 5 different ways and then the subject of the document signed his name using yet a different spelling). Additionally, the interpretation of hand-written documents often leads to misreading what was written by the clerk or individual. Think about all the different ways a name could be heard, and all the ways that certain letters can be confused.