the more I looked at this, the more familiar it became. I have finally determined why I recognized this and from where. (as you can see in the image below, there also exists a purple version)
in the very early days of the Kingdom of SHS, they had not established a National Bank, nor designed any banknotes for printing, yet (the National Bank of Serbia had not yet evolved into the State National Bank). in order to keep the economy in check and to allow commerce to continue to flow, the government regulated the usage of Austrian banknotes with these "banknote revenues" attached to them to attest that they were legitimized by the Finance Dept. I have seen a few different designs of stamps affixed to the banknotes, as well as just rubber stamp overprints, but all of these served the same purpose.
