The 16-year-old has matched the achievements of Patrick Hine, Peter Baker and a two-time major winner, Sandy Lyle.
Schmidt became the youngest winner of the English Men’s Open Amateur Stroke Play Championship (Brabazon Trophy) at Alwoodley in June.
He followed that up by completing the rare double at Moor Park Golf Club.
Schmidt faced Spain’s Rodrigo Martin in a play-off, and after the Spaniard could only manage a bogey on the first extra hole, his two-putt par was enough to lift the title.
“It’s been a tough day,” said Schmidt. “I’ve not played my best golf, or anything like it, but I dug in and eventually found something on the back nine to help me get across the line. It’s been a bit mad but I’m really enjoying it.”