Duffy made it four goals in the last three games with the opening strike in the Daniels' 2-0 home win over Long Eaton.
A late own goal then sealed Stamford's win which maintained their outside chances of reaching the Southern League Premier Division Central play-offs.
The Daniels made two changes to their starting line-up following the win over St Ives on Easter Monday.
Goalkeeper Dan Wallis returned from injury to replace the suspended Michael Duggan while Mike Armstrong came in for Tendai Chitiza.
The visitors were already relegated from the division and they fell behind after just six minutes of the match at a wind-swept Zeeco Stadium.
Tom Siddons played the ball out wide to strike partner Jack Duffy who cut inside before drilling home a low finish into the Long Eaton net.
Stamford came close to extending their lead shortly after only for a terrific treble save from Jason Alexander to deny the Daniels.
The towering goalkeeper kept out efforts from both Rhys Hilton and Lee Shaw before Riece Bertram cleared the next follow-up effort off the line.
Long Eaton enjoyed their best spell around the midway mark off the first half with Tom Hewlett going close on a couple of occasions and Bertram hooking another effort over.
Home defender Will Glennon then made a vital block from Liam Loughlan's well-struck effort before the visitors' Joseph Nyahwema made a crucial covering tackle to thwart Lee Shaw while Rob Morgan went close at the end of the half with an acrobatic overhead kick.
Stamford came out for the second half without the services of defender Ashton Offler who was replaced by Jon Challinor.
Both sides struggled after the break with the near gale-force conditions as clear-cut chances were at a premium.
Harry Vince brought a flying save out of Alexander with a sweet strike while Wallis did well to block a cross from Campbell-Gordon with substitute Nathan Tyson poised to pounce.
An injury to James Blunden then forced Stamford to play the final 15 minutes of the match with 10 men having used all of their substitutes.
But they had a great chance to put the contest beyond their visitors shortly after Blunden's departure when Shaw raced clear to latch onto a long clearance but he was again denied by the excellent Alexander.
The Daniels continued to defy the one-man disadvantage and doubled their lead in the 89th minute as Tendai Chitiza's cross was headed into his own net by substitute George Atwal.