A two-for-one package uncovers the radical early punkers in their prime, and well past it “can’t make out what has gone wrong,” Jon King sings on 1981’s “Paralysed,” evoking a marginalized worker. “I was good at what I did.” Gang of Four combined punk’s aggression with radical politics as well as or better than any other band of the late Seventies and early Eighties; they did this by forgoing the genre’s unchecked angst and perversely simple arrangements for a more rhythmically compelling approach to protest. This two-for-one collection of the band’s second and fourth albums isn’t prime material, but it has its moments. The ironically titled Solid Gold, the group’s second album, follows in the agitprop footsteps of G04’s 1979 masterpiece, Entertainment!; it’s not the statement that its predecessor was, but the band is searing on “He’d Send in the Army” and “What We All Want.” By the time of 1983’s mistitled Hard, it sounds as if the Borg caught up to Go4: They were almost all funk, no punk, and had swapped in a drum machine for a live player. Many bands could have survived a shift from punk to midtempo soul shimmying, but Hard makes it seem like the Gang’s mandate had been violated.