It looks like this Part has been superseded by LEGO Part 96907 Money / Coin with "10" Gothic Type.
Click on a colored part below to see the Sets and MOCs that use part 57504 Money / Coin with "20" Sans-serif Type in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
There are 6 Mold variations of part 57504 - Money / Coin with "20" Sans-serif Type in the database, in use between 1989 to 2011. See Molds and other related Parts.