Contreras, who was the fastest in the first run at Ofterschwang in Germany, was last out the slalom gate and produced another great display to deny Pärson victory by matching her combined two-leg time of 2min 22.18sec.
American Julia Mancuso came third in the World Cup event, which replaced the cancelled event at Maribor, at 0.9secs behind the winning duo.
The 30-year-old Contreras has been on superb form only a week before the start of the Turin Olympics, winning her second giant slalom of the season on Friday.
Sharing this win with Pärson, a former slalom specialist who has now become an all-rounder, means she remains one of the favourites for the slalom events in Turin.
But the result was a boost for Sweden, with two other contenders in the first eight.
Making her breakthrough in the top flight, Maria Pietilä-Holmner came sixth. Anna Ottosson managed to hold on to eighth place despite losing more than half a second to Pietilä-Holmner in her second run .
In the overall standings Croatian Janica Kostelic, who failed to qualify for the second run, continues to lead the way with 1282 points ahead of Pärson on 1121 points.