Olympic wrestling silver medallist Davit Modzmanashvili of Georgia and former Swedish 1500-metre world champion Abeba Aregawi both tested positive for meldonium, the same substance that Maria Sharapova tested positive for at the Australian Open.
Vakhtang Blagidze, a Georgia national wrestling team coach, says Modzmanashvili tested positive for the drug last month. He faces a possible life ban for a second doping violation.
Another five members of the Georgian team tested positive for meldonium but their names have not been released because they deny the charge.
Modzmanashvili won the men's 120-kilogram silver medal in Greco-Roman wrestling at the 2012 Olympics. He also won world championship bronze in 2011.
The federation says that none of the six were confirmed to compete at the Olympics in Rio de Janeiro in August, but that qualification was still possible.
Former Swedish running world champ caught
The agent of Aregawi says the Swedish runner's "B" sample has confirmed she tested positive for meldonium.
Aregawi was suspended last month by the Swedish athletics federation. Her agent, Jos Hermens, told Swedish broadcaster SVT on Wednesday the "B" sample showed up positive.
Hermens said Aregawi, who was born in Ethiopia but now represents Sweden, was cooperating with investigators from the International Association of Athletics Federations.
He said she took the medicine, which was banned on Jan. 1, thinking it was a vitamin supplement. Hermens said "she feels really sorry for all the people that she has let down in Sweden."