Paul,someone did say that they have been finding these error Presidential $1 coins in Tallahassee,Florida. It sounds like that these error coins are going to be very common. If you are taking them out of the rolls & you notice gouging on the edges,then chances are they have been damaged when they were going through a counting machine. Aidan.
SCNuss, what you are talking about is very common. I just read an article about who someone had a coin that got the edge printing twice and it was so precise that there are double lettering. Ex. GGOODD WWEE TTRRUUSSTT
But make sure you are talking to a dealer who specializes in errors. When it comes to errors 90% of the mainstream dealers have no idea what they are talking about. Error Dealer Fred Weinburg (I probably have the name wrong, I can never remember it.) has reported that over 40,000 of the plain edge Washingtons have been reported so far.
There are way more than 40,000 out there. The local coin dealer here is estimating 50,000 to 300,000. They have been tring to figured out how many coins are a batch to lower the 300,000 number. They know how many get shipped out together but not how many get made together.