The 25-year-old tested positive during the Indian Premier League competition held between April and June, and the Pakistan Cricket Board suspended him in July on the basis of his first sample.
"We have just completed the test on Asif's B sample and it has come back positive," his lawyer Shahid Karim told AFP by telephone from Switzerland.
"But I can tell you that the quantity of nandrolone has varied, which we can contest."
Asif tested positive for nandrolone in 2006 along with fellow paceman Shoaib Akhtar. He was banned for one year and Akhtar for two, but the bans were overturned on appeal.
Asif also faces a possible ban or fine from the Pakistan Cricket Board after he was detained in Dubai, while returning from the IPL, on charges of possessing an illegal drug.
He was held for 19 days before police deported him.