Double Dragon 3: The Rosetta Stone is Billy and Jimmy Lee's third arcade outing, in which they are joined by their long-lost sibling Sonny (wouldn't that make them the Triple Dragons then?).
Its biggest innovation was the introduction of item shops where players could gain access to new characters, moves and weapons...by putting even more quarters into the machine, basically microtransactions years before microtransactions were a thing.
Pictured is an early version of the character select screen, which was found unused in the US version and which would eventually be implemented in the Japanese version. Jimmy and Billy Lee could be selected individually, while the three other fighters were unique here instead of being grouped as brothers.