Sanderson has driven 14 winners in the first six months of the season, surpassing his best tally of 13 wins for a complete season (2010-11).
Sanderson (22) is in his fourth season as a junior driver. He is employed by the Invercargill trainer Wayne Adams.
Both his winners last night are trained at Longbush by Alan Paisley.
Princess Delight was at odds of 37-to-one in the third leg of Pick6.
• Pembrook's Delight broke a sequence of six minor placings when she led all the way last night.
It was the third win for the daughter of Bettor's Delight and Diamond Bright raced by Bill and Judy Bain, of Roxburgh and Judy Campbell, of Earnscleugh.
The mare is trained by Geoff and Judy Knight at Roxburgh.
Bill Bain paid $30,000 for Pembrook's Delight as a yearling as a prospective broodmare.
"I liked her as she was by Bettor's Delight out of Christian Cullen mare out of a Falcon Seelster mare," Mr Bain said.
He has the broodmares Ashanna (five wins), Onedin Dancer, Stylish Onedin and Careful Sez Nicki.
He will make is first offerings at the yearling sales this year - a colt by Mach Three from Stylish Onedin and a filly by McArdle from Onedin Dancer.
The Knights are partners in the filly.
• The 3yr-old trotters, Beau Brummell and Patch Bromac mastered the slushy track to record wins last night.
Beau Brummell is the first foal of unraced Lady Boo Kay (Sundon-Zola's Pride).
• Portobello trainer Steve Ashton produced Better To Be Bad to win in her first race four months. He races the Badlands Hanover mare with Miles Notman, of Dunedin and Gavin Chin, of Mosgiel.
