This statue in San Francisco, placed in the Golden Gate Park, is indeed an exact copy of the original monument that has stood on the Theaterplatz in Weimar since 1857. Not only that, like the original, the copy was also cast in Germany.
In 1899 it was cast from a plaster model of the original at a foundry in Lauchhammer located between Berlin and Dresden and shipped to San Francisco by boat and rail. Sculpted by Ernst Rietschel, the original statue was cast in bronze.
The San Francisco Goethe-Schiller monument was to be the first of at least four in the United States: Cleveland, Milwaukee and Syracuse, NY each have one. All are exact copies of Rietschel’s original 1857 sculpture. A fifth Weimar copy now stands in a town near Shanghai, China.