Double Backed One Hundred Dollar Bill

@Foolmetwice welcome to the forum! Unfortunately, I regret to inform that this is counterfeit. The weight is correct, and if the strip is glowing pink, then that's the right color too. However, the watermark (the face you see when placed in front of light) is wrong. It should look something more like this:

(Image taken from: https://www.uscurrency.gov/educatio...dollars-100)

Unfortunately, the watermark on your bill has a more cartoonish face than what would be on a genuine bill. For example, it has forehead creases (which are not present on genuine bills), thicker lines, and the jawline looks different.

to the CCF

I can think of no possible way that could happen (knowing how the printing works)
during the printing of the sheets of banknotes unless there was some inside help
which is also very unlikely. Agree with ANA about the watermatk.

Okay,Im reading the responses and I see your point about the watermark. However,the part that gets me is,if its a counterfeit why would the other side of the bill be inverted? A counterfeiter would make it look as correct as possible and would not have made one side upside down in relation to the other. Thats what pretty much convinces me that its real. Where I live there is no one that can validate it for me. Something else, who would go through all that for a fake bill that obviously wasn't meant to be used? And,I find it hard to believe that they could make both sides line up perfectly with each other

Where did you get it?
Are you out $100 or more?

I think a key indicator that it isn't genuine is it's condition. Just look at it: it appears to be extremely heavily circulated. Hundreds of people must have handled it, to make it look like that. And not one of those people ever noticed that it didn't have a front? People don't pay attention to singles, because they're such low value who cares if it's counterfeit, right? But a hundred is a lot of money, and people pay attention to them more.

No, it didn't get all dirty and grimy like that by actually being handled a lot. I suspect the counterfeiter deliberately roughed up their own fake, to make it look well-used and thus less suspicious (that's a very old trick from the counterfeiter's playbook). Remember, a counterfeit doesn't need to fool everybody, all of the time - it only needs to fool one person, once, and it's mission accomplished for the counterfeiter.

The only question remains, why did they make it double-sided to begin with? It seems to have been designed to pass casual inspection as genuine, so why not make it an even better fake and put the proper front on it? I suspect they may have made it "accidentally" (counterfeiters are much more prone to making errors like this than actual government printers) and decided it might still fool somebody anyway. Or if it was done deliberately, it might have even been a way to make sure the counterfeiter never received back one of their own fakes.