Rev 2:17: "... to those who prove victorious I will give ... a white stone - a stone with a new name written on it, known only to the man who receives it."
The white stone (the color of triumph and joy) symbolizes entry into the kingdom of heaven. The "new name" signifies the Christian's spiritual rebirth.
See also Rev 3:12, 19:2, and Is 62:2, 65:15.
Interesting question. When we are baptised our name is given. When we marry the names of each spouse are linked to each other and the woman name changes to the man's. We add another name when we are confirmed. A Pope takes a new name. I'm sure it means something.