So read on, and learn something Naming The Mario Bros. consist of Mario Mario and Luigi Mario. They are the Mario Brothers because their last name is Mario. This is why it isn't the Luigi brothers. By the time the game came into production in the US, though, the character was known as Mario. However, the main character in DK3 is not Mario, but an exerminator known as Stanley the Bugman.
Toad is the royal mushroom retainer of the Mushroom Kingdom.
The princess' name is Princess Peach Toadstool. The first name is Peach and the last name is Toadstool. Similarly, it is King Bowser Koopa. The first name is Bowser, and the last name is Koopa. This settles the double name issues.