The $20 bill has a unique serial number just like the nft.
It's even better because no one else can have that same bill at the same time.
There are some recent $1 notes where the same serial was issued twice.
https://www.mycurrencycollection.com/blog/1-2013-new-york-duplicate-serial-number-mistake
Still 2 different bills.
https://m.youtube.com/watch?v=A81DYZh6KaQ
The $20 bill has a unique serial number just like the nft.
It's even better because no one else can have that same bill at the same time.
There are some recent $1 notes where the same serial was issued twice.
https://www.mycurrencycollection.com/blog/1-2013-new-york-duplicate-serial-number-mistake
Still 2 different bills.
https://m.youtube.com/watch?v=A81DYZh6KaQ