Interesting. Not a currency collector but I noticed the light wide mark in the center of the obv curves to the left as it gets towards the base of the bill. Seems like it might be mint produced by one of the many rollers moving the sheets around. From what little I know, it seems like it's possible this came right after the portrait and wet ink got on the roller. Is there any way to confirm the shape of an embossed design on the rollers used by the mint? Seems interesting but would it bring much interest since it isn't a Del Monte sticker. LOL
Doh! (Said along with a Forehead Slap) Do you have much in the way of currency errors to go with all the coin errors?
Many, see this site for starters. They're usually very dramatic (obvious) and some not so obvious but you can identify them easily. I agree with @Mountain Man (more likely a teller's stamp) on the $2. We see these types of posts (& teller's stamps) often.