The Glovers, with coach Steve Thompson in charge following the departure of Russell Slade, fell behind after 18 minutes when Pipe volleyed home Duffy's cross after a touch from Jo Kuffour.
It was 2-0 on the half-hour mark as Duffy lost his marker at a Stuart Campbell free-kick and headed past Josh Wagenaar.
Substitute Lambert completed the scoring four minutes from time with a stunning 30-yard free-kick for his 21st goal of the season.
Yeovil's best efforts came from striker Paul Warne, who forced fine saves from Steve Phillips with efforts either side of the interval.
But the visitors, who were on a good run before Slade's controversial dismissal for undisclosed non-football reasons, looked toothless for much of the game.