When I lived in the UK, everyone insisted on calling me Tamara. I'd introduce myself, and sure enough, it was immediately and forever after the formal version of my name. I managed to convince my core group of family and friends they didn't have to be formal, but for the rest of the people I encountered, it was always Tamara.
People do this to DH all the time, although I think it bothers me more than it bothers him.
His family is British-Indian and he's got an Indian name, but shortens it to what happens to be a more common 'Western' name. People think they're being formal and showing respect by lengthening it to the full version... of the Western name.
Sorry, but that's not his name. Best call people by the name they introduce themselves as.
DH has a tough time calling my parents by their first names. He was raised to call elders by Mr and Mrs or the Punjabi equivalent.
After calling my dad Mr (surname) and my (very casual) dad insisting that DH calling him by his first name, he's started calling my dad 'Amy's Dad' or 'Mr-Amy's-mom's-husband, Sir' (both to his face).
It's pretty funny and my dad gets a kick out of it.
TF - there were 2 girls in my graduating class with the same first and last name. Both had brown hair and blue eyes. One was an ice skater. So they have forever been "ice skater Jessica Haynes" and "the other Jessica Haynes" 
Hehehe.
When I worked as an au pair in Switzerland there were three other non-Swiss girls in our group of friends named Amy.
One was Miss Amy (she was a teacher)
One was Aussie Amy (an Australian)
I was American Amy (although I never liked it)
The worst confusion we had was when it was my birthday. A few of us went out and at the end of the evening, one of the girls commented that it was (Aussie) Amy's birthday get-together and she didn't even show up.
Um, sorry, but it's MY birthday.
