paper Money is non-fungible, i know you've been told that one dollar = one dollar one pound one pound but you've been told wrong. 

The serial number on money means that not even one £5 note is equal to another case in point https://www-thesun-co-uk.cdn.ampproject.org/v/s/www.thesun.co.uk/money/2389798/5-pound-note-jane-austen-valuable-ak47-fiver-plastic/amp?amp_js_v=a2&amp_gsa=1&usqp=mq331AQEKAFwAQ%3D%3D#referrer=https%3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s&ampshare=https%3A%2F%2Fwww.thesun.co.uk%2Fmoney%2F2389798%2F5-pound-note-jane-austen-valuable-ak47-fiver-plastic%2F

Wow that was a long link, sorry about that... But my point is money can be worth more than it's face value but never less just think of coin collecting. 

Edit added this link to answer the question in the comments below 

https://inews.co.uk/inews-lifestyle/money/rare-valuable-coins-50-2-pound-circulation-how-much-worth/

Now for what this article is really about. Today the meticulous artist Tom Bradley has released his second artwork in his deplorables bank note series. Can be owned here.

https://opensea.io/assets/0x677d8fe828fd7143ff3cee5883b7fc81e7c2de60/293

This second note of Edward Snowdon is only available on the blockchain art exchange here

The notes are price at 1 Etheruem and that is the face value of the note. Now when someone buys the note for that price it will then become that value. There are 20 in total but of course they all have unquie serial numbers so 001 may sell for a bit more. 

https://opensea.io/assets/0x677d8fe828fd7143ff3cee5883b7fc81e7c2de60/293

But Toms work goes further than this what would happen if we started to put paper wallets into money I don't know what the implications of this could be but mabye Tom can explain better check the link here. 

You can also buy the frist in tom series here from 

https://t.co/nVzX2guVJy?amp=1

And be sure to get yourselves a note these are sure to be highly collectable pieces. 

https://www.bitcoin-banknote.com/2019/08/02/edward-snowden/