Sorry, but that is how it works. It is just not how it is supposed to work. :-P

Maybe they wrote a different value on each document as a fingerprint of sorts. Or maybe they just expected this to get out.

Probably the second one. Financial documents are typically prepared by lawyers and bankers, not cryptographers.

Or he asked his friend, "hey, can I see your document... yup, they're identical" and then leaked with impunity. If the public really wants something, and you send a document with that information on it to a bunch of people, it's going to be leaked. I think Goldman is smart enough to realize this; the buzz is helping their business, but they knew they would get in trouble if they just announced the numbers. So they just gave it to random people with a I-did-my-due-diligence-NDA and let entropy take care of the rest.

Hopefully the leaker was smart enough to perturb the values somewhat as well :)