I know how they'll feel when they figure out you're name is something else. I went to the same ice-cream parlor for 4 years and for the first 3 years I was sure the owner's name (also my neighbor) was Barry. And now I figure out his name's Wayne.
My landlord calls me a name that is a mish-mash of my name and my husband's name. I don't know why. Then when my mom moved here, he called her a name that isn't even remotely close to her name. We finally broke it to him. LOL