No one ever called mike T " mad dog". Thats bull shit.
No one called gotti " the dapper don". He was called johhny .
The feds create these names as well when doing undercover. Instead of saying joe russo over a radio, they might say " joey jackets" because he is wearing a jacket and the other joe isnt. These nick names are nonsense ( for the most part).
That said, there were a lot of nick names because so many italian hoods back in the day had a thousand petes, joes, vinny', nicks, johns, and joey's. The best way to distinguish was by a certain trait they posesses( johnny black/ jet black hair) or joey " arms" because of his muscles. These were basicqlly street corner names.