Josef Hoffmann Mark  

I picked up what appeared to be an early bentwood chair the other day which has a stamp for Josef Hoffmann and part of a paper label with "Wien" being the only visible word. Of course, when I got home, I noticed the spelling of Hoffmann is "Hofmann" on the stamp. Having a German last name that lost its original spelling once it was Americanized, I'm aware that sometimes the spellings get distorted across sources.....though, I'm assuming if you are stamping your furniture, you know how your name is spelled.:)
I can't imagine someone faked a stamp like this. Everyday people wouldn't recognize the name.
Any thoughts on the authenticity of the stamp or why there would be a difference in spelling? I'm including a pic of the chair (though it is not terribly unusual) just so you can see the chair the stamp was on.
Thanks for your thoughts,
Sandra