The evergreen St Kitts and Nevis sprinter had already clocked 6.52sec in winning the Dusseldorf event on Thursday.
“I`ll start nine more events this season,” Collins, the 2003 world champion, said.
“It`s a serious challenge for me and I`m taking every new start as if it`s my last.”
American Mike Rodgers, who served a nine-month doping ban in 2011 and was third in Germany behind Collins, was second Sunday in a time of 6.56sec. Yunier Perez of Cuba came third, 0.05sec further back.