Duda had a ground-rule double during New York's two-run first and he hit a solo homer during a three-run sixth. Murphy blasted a two-run homer in the second that gave the Mets a 4-0 lead.
Jonathon Niese (11-9) gave up two Milwaukee runs in the second and nothing more over a six-inning appearance. He left with a four-run cushion and four relievers protected the advantage by allowing one hit over the final three frames.
The loss was charged to Mike Fiers (9-8), who was roughed up for four runs on eight hits in four innings. Milwaukee had won its previous three games.