Naming twins

[xoxoxoBruce]

Social Security Online has a list of the top 100 pairs of names given to twins born in 2006.
The top ten;
1 Jacob, Joshua 67
2 Matthew, Michael 54
3 Daniel, David 52
4 Ella, Emma 38
5 Isaac, Isaiah 38
6 Madison, Morgan 36
7 Landon, Logan 35
8 Taylor, Tyler 35
9 Brandon, Bryan 34
10 Christian, Christopher 33
use the same first letter for both names. In the rest of the list the matching letter holds sway.

Why do they do this? Why make the kids use three initials to tag their stuff? If they do the same with the middle initials it makes it really tough.
I don't get it.