An encore screening of Vincenzo Bellini’s opera “Norma,” which opened the new season of the Met: Live in HD two weeks ago, will take place at Guild Hall on Saturday at 1 p.m. The new production of the bel canto tragedy is conducted by Carlo Rizzi and directed by David McVicar. It stars Sondra Radvanovsky in the title role, which the soprano Renata Scotto has called “the Everest of opera.”