The Kiwis, who were runners-up at the world championships, finished comfortably ahead of the established Australian pairing of John Dalla and Ken French.
The win completed a double, after Dobbs and Oldfield won their first test at Waimate on October 14.
Geraldine blade shearer Allan Oldfield was runner-up to French in the Bendigo Blades final, beating both Dobbs, who was third, and father Phil, who was fifth.
The world woolhandling champion team of Joel Henare and Maryanne Baty, from Gisborne, defeated Australians Mel Morris and Sophie Huf. Henare took his tally of Open-class wins to 94.
New Zealand has now won 29 out of 38 transtasman woolhandling tests since 1998, and all nine blade-shearing tests since regular transtasman contests began in 2010.
However, Australia has a 32-30 advantage in the machine tests since a regular home-and-away series started in 1974.
Its record was reinforced in Bendigo, where the Australian team of Daniel McIntyre, Shannon Warnest and Jason Wingfield beat Shearing Sports New Zealand shearers Rowland Smith, John Kirkpatrick and Troy Pyper by more than 40 points in the machine shearing test.
Two days later in Warrnambool, New Zealand had a near clean sweep in the top Australian crossbred shearing competition. However, home show representatives Glen Stephens, Tyson Scholz and Lee Harris beat the New Zealand Shears Te Kuiti team of Mark Grainger, David Buic and Dion King in a transtasman challenge that included merinos.
Grainger won the Open final over Buick and King, Victoria-based Balclutha shearer Karipa Tumohe won the Senior section, and Hamilton's Sean Gouk won the Intermediate event.
Gisborne woolhandler Keri Henare, Joel's cousin, took the Open woolhandling title from Alexandra sisters Pagan Karauria and Larnie Morrell. The Senior section went to Port Waikato's Wilz Marshall.
South Islanders are at the top of six of the eight Shearing Sports New Zealand rankings after the first month of the season.
Eight of the season's 61 shows have been taken into account so far, five in the South Island and three in the North Island. The rankings are based on points for placings in finals. To make the leaderboards, competitors have to have reached at least two finals.
Rankings have been compiled each season since 1994 and the top competitors are recognised with presentations at the New Zealand championships in Te Kuiti.
Timaru former New Zealand representative Mike McConnell heads the blade shearing rankings, being the only competitor to have shorn more than one final in the three blades competitions to date.
The Open shearing rankings are led by Southland's Nathan Stratford, who won two of the three South Island finals he has reached. Fellow Southlander Troy Pyper, who was runner-up at Alexandra and Waimate, is second, followed by defending rankings champion Rowland Smith from Hawkes Bay.
Ranfurly's Vahni Stringer is at the top of the Senior shearer rankings, the Intermediate leader is Woodville's Daniel Seed, and South Island-based Darcy Tong heads the Junior listings.