Williams usually got the sole screen credit, perhaps because of the two themes (talk about night and day.)
Williams got the theme credit, but a solo “music” credit (he was “Johnny” Williams back then) when he did the score, too. The others got screen credit when they did original scores, not when music was reused (such as Herrmann’s, which must have ticked him off—he flew into a rage when Jerry Goldsmith’s “Music by” credit appeared on a TV episode of something while Herrmann’s THEME music was playing).