A number of top QBs have had horrible games where they threw multiple interceptions, many more than one.
NFL Passes Intercepted Single Game Leaders. Here's a sampling:
Ken Stabler: 7
John Brodie: 6
Joe Namath: 6 (3x)
Norm Van Brocklin: 6
Brett Favre: 6
Peyton Manning: 6
Joe Ferguson: 6
https://www.pro-football-reference.com/leaders/pass_int_single_game.htm