How sure are you of that? Since about 8 years ago almost every paper bill in my area went counterfiet. It still passes, but it's all made on a copier.
Well, we got a real one from the bank doing the training on the differences which had a "supernote" on loan from the treasury department for the training.
Our bank is very proactive in training small business owners, which is why we bank there. We take in a lot of hundreds (auto repair) as payment, so we try to stay current.