Jonathan Rea dedicated both of his victories to Jason Dupasquier following the Swiss rider's death on Sunday.
Dupasquier, 19, crashed in a Moto3 race at Mugello in Italy on Saturday.
Rea won both of his World Superbike races in Estoril, Portugal on Sunday, including the earlier Superpole event.
Speaking after his second win, Co Antrim rider Rea said: "It's been a great weekend for me but there's a real sour taste in my mouth after the news earlier about Jason.
"It's terrible. I want to dedicate that to him and his family. I hope it gives them strength at this time."
Northern Ireland's Rea now leads the World Superbike championship by 35 points, ahead of Toprak Razgatlioglu with Scott Redding one point further back.
Reflecting on Sunday's race action, Rea said: "I was catching Scott quite quickly. I plotted a move at turn one, he came back and the next thing I know he is out.
"I'm sorry for him because that was a nice little battle for those few corners. I really didn't expect to win here."
