Take a close look at those digits. They're from one of these old stamps doohickies:
It would be very easy for any column of numbers to get LESS ink on one of those stampers than the others. More some with the right-most numeral, since that would change for each stamping. (The other numbers would pick up more ink since they are struck against the pad repeatedly as the sequence of numbers is stamped out.)
So, in this case, if someone was stamping a stack of these, it's highly probable that the "1" simply received less ink, and was therefore slightly lighter when the digits were applied. It is also possible that the stamp was not applied to the paper perfectly vertical, thereby causing the right side to come out slightly less light.
Now, depending on the sensitivity of your scanner, the slight change in shade could scan the other digits as BLACK and the "1" as a dark gray. On the gray-scale, it gets anti-aliasing, but black doesn't. (Which would give dark black a sharper appearance on scanned images - a desirable quality.)
So, in conclusion, I don't think the difference in the number "1" means anything. In fact, if you look carefully through the document, you'll even see anti-aliasing applied in a few places to text and lines on the original form - that is, very slight differences in color/shade leading the scanner to scan those as gray and the other lines as black.
If this is a forgery, they did all the work necessary to make it nearly 100% bullet-proof. We should move on and keep the pressure up on his POLICIES or risk being marginalized. Watch these FR threads closely: you'll see many thoughtful Freepers moving away from the BC issue and a few fanatics holding on in desperation. Watch the politicians and pundits - even Trump has accepted it. Obama has been right about only one thing: this BC issue is a distraction.