If you study the green bc closely, you will notice that someone overwrote the "unham 0bama" portion of Ann Dunham Obama's signature so as to modify it so she'd appear married. You can see that someone used a different pen only on that part of her signature.
If they had ADDED just "Obama" after Ann Dunham using a different pen, that would've been too obvious so they started the overwrite earlier in her signature so it would look more believable.
The joke's on us.
If you study the green bc closely, you will notice that someone overwrote the "unham 0bama" portion of Ann Dunham Obama's signature so as to modify it so she'd appear married. You can see that someone used a different pen only on that part of her signature. I seem to recall that a smiley face and some other obvious mistakes were made by the forger....
It was postulated at the time that these were some sort of "insurance" placed by the forger to avoid taking tea with Polonius (a dirt nap in Fort Macy Park for those in Rio Vista).