The Business of Fake Hollywood Money
There seem to be a lot of possibilities that would do in various positions.If you could make the money feel distinctively different, while appearing the same, it would probably be enough to cause a receiver to pay sufficient attention to notice the minor differences.Printing different denominations on each side of the bill would be sufficient for most stationary money.For scenes with large amounts of free flowing money,  you could print the notes backwards and flip the film.I don't think there would be any single solution for all instances, but I think you could pick a form that would suit whichever scene you were currently shooting.