There's an unused model of Mario in the game's data. Mario is stretched to Luigi's proportions and is equipped with the back straps for the Poltergust 3000. The geometry of the model is simpler than Mario's final in-game model, containing fewer polygons. Although its true purpose is unknown, it could've been from an unused multiplayer mechanic requiring both Mario and Luigi. The model was stretched out, presumably to fit Luigi's skeleton so that Luigi's animations could be used on the model. The model also uses Luigi's gloves, presumably to make his animations handling the Poltergust 3000 more accurate.