Ryan Lochte of Daytona Beach Swimming, who now shares the world record in the 200m back with Peirsol, finished second in both races by just fractions of a second, touching in 1:54.34 in the 200m back and 1:55.22 in the 200m IM.
In other finals, Rebecca Soni of Trojan Swim Club won the women's 200m breaststroke in 2:22.60, while Dara Torres of Coral Springs Swim Club captured the women's 100m free in 53.78.
The first- and second-place finishers in each of tonight's finals - along with the top four finishers in the women's 100m - free qualified for the U.S. Olympic Team. A number of swimmers who finished second in their events earlier in the week were also officially added to the Olympic Team Friday.
Those swimmers included Lochte (400m IM, 200m IM, 200m back); Peter Vanderkaay of Club Wolverine (400m free); Mark Gangloff of Swim Mac (100m breast); Matt Grevers of Tucson Ford (100m back); Gil Stovall of Athens Bulldog Swim Club (200m fly); and Eric Shanteau of Longhorn Aquatic Club (200m breast).
In the men's 200m backstroke, Peirsol and Lochte were stroke-for-stroke the whole way, with neither swimmer enjoying more than a two-tenths-of-a second lead over the other throughout the entire race. The two touched the wall almost simultaneously, and the crowd of 13,247 at the Qwest Center Omaha drew its breath and looked at the scoreboard. Peirsol first, Lochte second.
It was Peirsol's second win of the meet after taking the men's 100m back in world record time on Tuesday.
"I was just trying to make the team," Peirsol said. "I knew going in what kind of race it would be. I didn't know if we were going 1:55 or 1:53, but I was happy to get my hand on the wall first.
"It's much more fulfilling to win a race by two-hundredths of a second than it is to win by two and a half seconds."
Lochte had just about 25 minutes between races before he was up on the blocks again, facing Phelps in the 200m IM. Though Phelps led for much of the race, Lochte took a slight half-second lead at the end of the breaststroke leg, setting up the battle down the homestretch.
Phelps edged Lochte at the finish by 42-hundredths of a second, as the crowd stood up on its feet and cheered his world record. Lochte's time was the third fastest of all time in this event.
For Phelps, the 200m IM was his fourth win of the week, after taking the 400m IM, the 200m free and the 200m fly. He has qualified for the Olympics in five events, including the 4x200m free relay.
"I think both of us hate to lose," said Phelps, referring to his and Lochte's competitive drive. "When getting in the water with him in the last three or four races, it's taken a world record to win"
Both Peirsol and Phelps applauded Lochte for his double effort Friday.
"I like the events I'm swimming," Lochte said. "I'm a versatile swimmer, and any time I get a chance to race a swimmer like Michael Phelps or Aaron Peirsol, I'm more than happy to do it."