The two Mebusts, Frevele and Zenir touched in 1 minute, 47.37 seconds to easily break the school record of 1:50.65.
Cooperstown finished third in the 12-team meet with 328 points. Holland Patent won with 442, followed by Weedsport at 343.
The 200 medley relay marked one of several Redskins school records set Thursday.
The Mebusts, Zenir and Eamonn Maguire broke the school record in the 400 free relay. They finished second in 3:36.45, eclipsing the mark of 3:38.96.
Both teams will compete at 12:30 p.m. Saturday in the Section Three State Qualifiers at Hamilton College.
Sean Mebust also qualified in the 200 individual medley and the 100 free. He won the 200 IM in 2:10.83 and finished second in the 100 free, in a school-record 51.35.
Erik Mebust qualified in the 100 backstroke and the 200 free. He finished second in the 100 back (58.77) and set a school record in the 200 free (1:56.06). The record in the latter event was 1:56.99.
Zenir will swim in the 100 butterfly and the 500 free. He lowered his school record in the 100 butterfly, touching second in 57.62. That took close to a second off his previous record.
The Redskins’ Aaron Idelson will compete Saturday in 1-meter diving. He won that event with a score of 331.80 points.