They are real bills but they are all out of circulation, so in general they are usually older. My company makes the dye packs, but we ship them out without the money, I have a complete kit at my house and all of the bills are from the 90's.
The bank provides "bait money", which are bills with recorded serial numbers. The idea is when you are inevitably caught having that on you is another nail in the coffin. Also, don't rob banks,