My Dad hated his real name, so he had a nickname that everyone in the family called him. Some of our neighbours misheard it and thought it was "Dick" so always addressed him as that. He was also known by another different name at work and sometimes used his middle name when introducing himself to new acquaintances.
So when I started school and the teacher asked me what my father's name was, I replied, "Well, it's either Tom, Charlie or Dick." The teacher looked horrified - I can imagine what she was thinking!!
I had to use another version of my name when I changed jobs at 20, because someone else in the office had the same name as me. So my siblings, wider family and pre-20s friends call me one thing and my husband, daughters and post-20s friends call me another...it causes confusion sometimes.