Keep in mind, the material can be duplicated or close to it, all the intricate markings/seals that I mentioned, _cannot_ be. Counterfeiters don’t have printing process materials/scan tools to replicate all the counterfeiting skills perfectly. It’s basically near impossible to alter all of the counterfeiting details that are included in a bill today.
The new $100 dollar bills now have a physical strip that goes across the bill itself, almost like it looks like a piece of tape. What counterfeiters will do, is when they duplicate the bill itself, they’ll take the bills and slightly rinse them underwater, dampening them, then they take multiple fabric dryer sheets and the bills combined, put them in the dryer for like 5 to 6 minutes on high heat, and it will give it the texture that it’s actually like a genuine bill itself, then they’ll use an iron to flatten the bill out. This might sound strange, but a counterfeit bill itself will actually have a slightly different odor if you smell it compared to a genuine bill. (Yes, I’m trained to notice everything.)