I do geneology, and maybe I can shed a little light on the subject.

[SeumasA]

My ggg-grandfather sold a Revolutionary land grant, and the document, written in one hand (not his), spelled his name three different ways on the same page.

I've run into that too. I have a fairly common last name--Allen--and I've seen it spelled Allan, Allen, Allin, Allun, Allyn etc., sometimes two or three different ways in the same document.