I thought the K2 Poacher was the first "new school" twin, a NY times article dated Feb 01 1996 discusses it, presumably as a model for the 1997 year.
Some Google research shows it as a 1996-1997 model ski, Line Skis founder built some in 1995 as part of a school project as well.
1996: As the parks were just for snowboarders, the ski companies try to design new Freestyle Ski. They finished in ridiculous hybrids of ski-skiboard with large sidecuts. K2 Poacher is the only twintip full-size although only 162cm and 69mm of sidecut- taking the title of the first twintip modern, two years before the Salomon Teneighty.
1995: The student design Jason Levinthal creates a couple of twintips short for the final project at the University of Buffalo.
The summer after graduation built a press in the garage of his parents and began producing skiboards. Line Skiboards now known as Line Skis was born.
Solly 1080 is regarded as the first successfully marketed new school twin,