In one corner, the enigmatic Emily Dickinson; in the other, the emphatic Walt Whitman. An audience watched the two throw poems like punches during the MAC’s May 3 event, “Dickinson vs. Whitman, the Poetry Knockout!” Stephen Collins was back in the Tri-Town as Walt Whitman, facing off against the Tri-Town’s own Annemarie Fredericks in poetic fisticuffs.