Tracey, the "where's George" Forum has people who talk about dollar bills and what is "valuable" by numbers.

https://www.wheresgeorge.com/

Cool Numbers give you a rarity of numbers on a dollar bill

http://www.coolnumbers.com/

So of course bills with the same digit is the rarest find, you then can have binary bills-2 digits, birthday bills, tombstone bills, radars, ladders, semi-ladders, and many other "odd" bills.