My dad always calls GM by the long version of his name rather than the version he actually, you know, uses. That's because GM was named after my dad's deceased brother, who always used the long version of the name, so I can understand it; but at the same time, it confuses people outside the family. Because usually a parent only uses the long version of a name when they're mad at the kid, you know?
So it always sounds like Dad's mad at/doesn't like GM. Oh and he calls me by the short version of my name (I was named after his mom), but he still can't spell it the way I prefer it spelled.
I don't think he cares that I have a preference though.