Originals are hand signed and numbered. If all ink is the same solid black, they're prolly fakes. Printer's ink stays black, pen ink fades to brown, blue, green and reds, and sometimes eats through the paper.
Real notes were normally printed on rag paper, just like today, even well-worn notes look like wrinkled clothes. Fakes are often found on brittle paper that looks like kaughy was spilled on it. It would be foolish to print on brittle paper, the second time it was folded, you'd have to trash it.