The "B" samples of Bjorn Basson and Chiliboy Ralepelle confirm that the Springbok players took a banned stimulant during the world champions' tour of Britain and will now face a South African Rugby Union tribunal.
Basson and Ralepelle failed random doping tests for methylhexaneamine after South Africa's victory over Ireland on 6 November 2010 and were sent home from the tour. They blame a sports drink used by the squad.
"The players will not contest the testing procedures or related matters under the 2010 autumn internationals anti-doping programme, and therefore the investigation and hearing will be conducted in South Africa," SARU said.
A date for the hearing and the names of the members of the tribunal will be announced next year once investigations have been completed, SARU said.
The 23-year-old Basson, a winger who was on his second Springboks tour, was already due to return home because of injury before he was sent back. He hurt his ankle in the match against Wales, his fourth international appearance.
Ralepelle is a hooker who has won 18 caps for South Africa.
Beginning next year, the World Anti-Doping Agency will loosen the classification of methylhexaneamine to the "specified stimulant" list, which covers drugs that are more susceptible to inadvertent use and can carry reduced penalties.
Sanctions for using the drug can be reduced if athletes prove they did not intend to enhance performance. Penalties can range from a warning to a two-year ban.
(Sapa, December 2010)