Top two images: in Luigi's Mansion, the bills found throughout the game as one of the money collectibles are worth 20,000 G each.
Third image: however, looking very closely at the bills in-game reveals they actually read "10,000" on them.
Last image: extracting the textures for the bills from the game's files confirms this. The bills (note that green and brown bills are actually just two cosmetic skins for the same item and have no functional difference) all read "10,000 G" or "10,000 GOLD".
It is clear that the developers originally intended each bill to be worth 10,000 G and then "rebalanced" the money value to be 20,000 G. It is possible that the intent was that it would be too difficult to see the texture at the game's original resolution for this to be an issue.
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