Former Darlington striker Main, who recently scored four against Chester-le-Street, scored before the break to further his claims for elevation to Boro's first-team squad.
Ryan Brobbel, Curtis Edwards and Charlie Wyke were also on the scoresheet in a high-scoring encounter.
Middlesbrough: Ripley, Pilatos, Reach, Dolan, Oliver, Jackson, Dobie, Edwards, Fowler, Brobbel, Main.
Source: Northern Echo
Source: Northern Echo