I remember an hilarious chapter in
Good Omens describing the roll of the Army of Light; since it was all a fake, all officers had the same name: Smith, up to the lance corporal (or somesuch) degree. From there on, it was Smythe, Table, chair and so on. I guess it was due to a (maybe momentary) lack of imagination. I also remember one of the Tom Clancy novel describing a system for creating slightly different copies of "top secret" documents, so that, when one was leaked, the culprit could be found straight away.
Looks like the DoD is a bit more like the former than the latter. They have
faked a letter by a GI and sent it to several regional newspapers. The only thing that has changed is the name, batallion and signature of the purported grunt.
Was it so difficult to find real soldiers, with real names, to write real letters? If privates and corporals and sergeants grammar and spellign were not up to par, they could have tried lieutnants. Or captains. Or the Commander in Chief himself... well, maybe not him. But I'm sure Rummy could have written several dozens of perfect letters.