A Queensland man has mistakenly bought a second identical ticket online and unintentionally doubled his winnings from Saturday's Gold Lotto draw to almost $2 million.

The Sunshine Coast man, aged in his 40s, was celebrating his single winning ticket when lotto officials called him to say his prize money had doubled thanks to the very fortunate mistake.

The Queensland man's favourite numbers, which he plays regularly, came up trumps over the weekend.

"Oh my god. I’ve got double that win?" the anonymous winner said.

"So I’ve got more than $1.98 million? Mate, you’re kidding me, you are kidding me! Today, you‘ve changed my life, man.