What's in a Name?

My colleague is having twin boys, due sometime in the next two months. Some of my favorite suggestions for names so far are:

1. Name them both the same thing
2. Name them both the same thing but spelled differently (ie, Sean and Shawn)
3. Name them both different permutations of their parents first and last names so everyone in the family has a name composed of the same set of elements
4. Name them "First Name, Last Name" to make filling out paperwork easier (or simply surreal)
5. Name them different things but switch their names often (ie, if one is Adam and the other is Sam, decide one day to start calling the first Sam and the second Adam)

Which made me wonder: if you and your identical twin were to switch names with each other at the age of 30 or 40, that would constitute a recognizable, clearly defined change. Likewise if you switched places at the age of 15 or 12 or 7 or 5. But what about at the age of 3 months? What about 2 months? Some babies don't have names at all for several weeks, so what difference could a change make after one or two weeks or even a few days? And yet, imagine bringing 2 babies home from the hospital and, several days later, reversing what you call them? It seems questionable at best. I guess what I'm really asking is this: at what point do you become your name?