A system and method for reducing modal coupling of combustion dynamics generally include multiple combustors, and each combustor includes multiple fuel nozzle groups for mixing fuel with a compressed working fluid prior to combustion. A fuel circuit is in fluid communication with each fuel nozzle, and orifice plates in the fuel circuit upstream from the fuel nozzles control the fuel split between the fuel nozzles in each combustor and/or between different combustors to produce a frequency difference between combustors.