The Saints started well, taking a 10th minute lead through Danny Kelly, only for the Duns to level five minutes later with a goal from Alex Cathline.
But four minutes before the break, Josh Dawkin restored the Saints` lead and Kelly`s second of the game seven minutes into into the second half won it to lift the hosts level on points with fifth-bottom Cirencester Town.
Tuesday`s other Premier Division game saw inconsistent Kettering Town show their good side with a 2-1 win in their first visit to Kings Langley.
The Poppies fell behind to a 54th minute Jorell Johnson effort. Just three minutes later though and the visitors were back on level terms with a terrific 30-yard drive from Liam Canavan. And then two minutes from time, former Corby Town favourite Paul Malone won it for the Poppies.
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