We named people when I was in college the same way, and the names stuck for years.
It happens in the military too.
Even at work in large facilities.
Anywhere a group of people spend a lot of close time together, they are likely to get a nickname if they stand out for some reason.
I worked at a plant once, when a new young engineer came to work. His name was Gary. This plant already had 4 Gary's in the technical structure, they told him to pick a new name, he thought they were kidding so he said "Rick". He became Rick. Everyone called him Rick, and next to his initials and last name on the phone list, in parentheses it said Rick. To the company, he was officially Rick until he left a couple yrs later.
Not that unusual either, many oriental employees pick an american first name to use because their actual names are too difficult for people to pronounce, they just arbitrarily choose a new one to go by at work. Either that or get called some shortened version of their last name , sometimes just the first syllable.