This is my last attempt for awhile, but after searching through all of my paper bills, I noticed that this $20 has funny lines and what appears to be JA on Andrew Jackson's face. I've looked at it with a loop and to me it looks like those letters & marks are underneath the normal printed dots. Is this a legit error or just PMD? IL 01267973 F L12 Series 2006 G1 on left corner, G402 on right corner This pic is zoomed in a bit more to show the dots on top of the lettering:
Questioning everything that doesn't look right is the correct way to do it. Don't give up. They're out there, you just have to be vigilant...and lucky. Everyone here is always willing to help. You just can't be offended when told the truth. You'll have many more misses than hits.
I agree that it is part of a tellers stamp. The edge of the stamp can be seen running through the portrait. The JA is probably part of a date JAN.