Dave McMillan struck twice for Dundalk as the champions claimed the points from Friday night’s Premier Division meeting at Finn Park.
The striker opened the scoring on 33 minutes, converting a wonderful Vemmelund delivery in past Ciaran Gallagher.
Then after heading against the crossbar shortly after half-time, McMillan made it 2-0, guiding home a cross from the Conor Clifford.
Harps played well, but created little in the way of decent openings, although they did have strong appeals for a penalty denied late on when the referee chose instead to award a free out, despite a visiting defender handling the ball.
