At Monte Carlo, the two-time Olympic medallist further added to his hardware by posting a time of 3:49.40, behind South Africa's Myles Brown. Germany's Florian Vogel was a quarter-second behind Cochrane for the bronze.
The 26-year-old, of Victoria, B.C., claimed gold in the serie's 800-metre freestyle on Thursday.
Cochrane's Victoria teammate Jeremy Bagshaw was eighth in Saturday's race, touching the wall at 3:56.49.
Canada's Pan Am athletes were active at the meet, with Kierra Smith placing fourth in the women's 100-metre breaststroke.
The result bodes well for the Kelowna, B.C. native, who will compete in her specialty 200-metre breaststroke on Sunday.
"I was really happy. I'm getting close to that season-best time I had at [National Team] Trials and that feels pretty good," Smith said.
"It's exciting for tomorrow, because I'd like to go out that much faster. To race the best in the world, I'm going to need that speed and I am going to try to do it again."
Sixteen-year-old Mary-Sophie Harvey, of Montreal, Que., swam to an eighth-place finish in the women's 200-metre backstroke, clocking a season-best 2:16.88 during morning qualifying.