20 US Dollars with 'unique serial number'?

So I saw this auction today, and the guy is selling a 20 US dollars with a 'unique serial number' with starting bid of 12.500 Serbian dinars (about 100 euros)

Here's the photo


What is so unique about this number?

Here's the auction link
https://www.limundo.com/kupovina/Numizmatika/Novcanice/Amerika-Australija-i-Okeanija/20-Dolara-Jedinstven-serijski-broj/60018961

Technically he isn't wrong because that's the point of the serial number ... to be one of a kind
Although it's nothing special ... maybe because the 666 he thinks it's ominous or whatever.
Sadly their are still very many bronze age desert people folklore believers in this world.

The Serial Number starts with ML. I am no expert, but most US banknote serial numbers start with one letter, not two. That is probably what this person is referring to.

I think that's only the case for the 1 Dollar, 2 Dollar and older bigger bills.

Verweis : "JRo69"​The Serial Number starts with ML. I am no expert, but most US banknote serial numbers start with one letter, not two. That is probably what this person is referring to.

​All US banknotes $5 and above have a two-letter serial prefix since 1996.

Well here a one dollar , just a little more ominous

Verweis : "Cerulean"​

Verweis : "JRo69"​The Serial Number starts with ML. I am no expert, but most US banknote serial numbers start with one letter, not two. That is probably what this person is referring to.

​​All US banknotes $5 and above have a two-letter serial prefix since 1996.

Thank you for the clarification. I was not aware of that. Guess I need to get more money above $5 bills.
​

Verweis : "ALLRED1950"​Well here a one dollar , just a little more ominous
​

​I guess "666" in the serial number is more attractive than "6666"