Mack had emerged from the pits ahead of Salmon in Race 2, the pair battling until the penultimate lap when Salmon finally found a way through in the Ferrari 458 GT3.
However the positions were reversed post-race, with Salmon relegated to third after a five-second penalty was applied for a jump start.
Mack experienced a mixed weekend, having started from pit lane before charging through the field to fourth place in Race 1.
His results saw him claim fourth for the weekend, narrowly missing out on a podium as the consistency of Steve McLaughlan (Valvoline Jamec Pem) saw the points leader bank important points in the title race.
McLaughlan had fallen to fifth early in the opening race, dicing with the impressive Aaron Cameron in the opening laps, before a measured performance in Race 2 saw him add 145-points to his tally for the round.
The impressive Cameron claimed the MARC Class victory in both of the weekend's races, while Brad Woods and Tyler Everingham combined to take second for the round. John Goodacre (Gap Solutions/SEKTOR) secured third in class, while Jake Camilleri struggled with mechanical issues across both races despite demonstrating strong speed.
Challenge Modern class went to Mark Griffith (Griffith Corporation), who raced his way into the top ten in Race 1 after starting from the rear of the grid.
He recorded another top ten in Race 2 to secure class honours ahead of Scott Hookey (Fiorano Motorsport) while Ferrari confirmed all three class podium places courtesy of John Nikolovski and Jamie Arratoon who shared the Arakin Racing Ferrari 458 Challenge.
Gartner's perfect weekend propels him to third in the points standings with 391points, overhauling Rick Mensa (301pts) who nursed a long brake pedal to the flag in the second race.
Two podiums see Salmon edge closer to McLaughlan at the top of the standings, the Valvoline Jamec Pem racer now just 87points clear at the top of the standings with two rounds remaining.
Salmon also reset the Queensland Raceway lap record, lowering the benchmark to 1m10.990s midway through the opening race, shaving almost a second and a half off the previous marker.
The CAMS Australian GT Trophy Series presented by Pirelli now heads to Phillip Island for Round 3 (September 8-10).
Australian GT will next be in action when the CAMS Australian Endurance Championship heads to Sydney Motorsport Park on August 18 - 19.