Of the millions and millions of plates in California, 1225 are 2 characters long.
Only 35 are 2 characters long AND feature repeating characters.
Only 12 of the 35 are aesthetically symmetrical.
These make up the Divine Dozen.
AA, HH, II, MM, OO, TT, UU, VV, WW, XX, YY, 88
As of May 2022, only seven are registered to actual vehicles. This means 5 (including MM) are held on retention by their owner or they have been removed from the system entirely.