She captured the 200-yard freestyle race in a personal-best time of one minute 49.57 seconds, just less than an hour before claiming the 500 freestyle (4:49.79).
"I'll have a special place to put these medals. Maybe I'll put them in my living room for everyone to see," she said.
Her latest round of excellence came in the aftermath of winning both races Friday in the Division I finals.
Sun said the past week was exhausting, but she managed to keep her momentum.
"I'm so happy and it's a great feeling," said Sun, who's the reigning All-Area Female Athlete of the Year. "It proves that my hard work paid off."
Sun recorded the ninth-fastest mark in CIF this season in the 500 and became one of 10 athletes to record a time under 4:50.
"I really wanted to go under 4:50 this season," said Sun, who led throughout the entire 20-lap event to beat La Serna's Samantha VandenBert (4:53.82). "It's slowly sinking in already with this and everything that happened last week. I'm really overwhelmed."
In the 200, Sun clocked 54.16 through the first half of the eight-lap race. She won by a body's length against El Segundo's Mattea Perrotta (1:50.16).
Crescenta Valley girls' Coach Robert Miller said Sun came prepared to compete.
"It's all mental with her," Miller said. "She sets her standards high and her pacing was right on the dot.
"She was sending a message that she'd win the races and she made her mark."
In the diving event, La Cañada junior Edgar Simonyan took second with 268.95 points. Teammate John Geyer, who won the Division II title on May 9, was fifth (237.80 points).
Crescenta Valley's David Corless took ninth (208.10).
Christian Lawrence of La Cañada was seventh in the 100 breaststroke (59.18). Crescenta Valley's James Martin took fourth (52.06) in the 100 backstroke, while La Cañada's Ian Mirasola was sixth (52.78).
La Cañada placed fourth in the 200 medley relay (1:39.4) and sixth in the 200 freestyle relay (1:28.80).
Crescenta Valley girls' freshman Yumi So was fourth in the 100 butterfly (56.91). The freshman took second in the consolation heat of the 200 individual medley (2:07.19)
La Cañada boys' swimmer Andrew Nguyen, who helped the Spartans win the Division II crown Saturday, won the consolation heat in the 200 freestyle (1:42.60) and the 500 freestyle (4:35.99).
Martin finished third in the consolation heat of the 100 breaststroke (59.68).
La Cañada's Jerrold Lee took fifth in the consolation heat of the 500 freestyle (4:42.55).
Spartan Tim Aguilar clocked 52.20 to take fourth in the consolation 100 butterfly. Teammate Devon Borisoff placed seventh in the 50 freestyle consolation (22.69).
Mirasola was third in the 200 IM consolation (1:57.30) and the Crescenta Valley boys' 200 medley relay took second in 1:40.21.