The component m is declared multiple times in Modelica.Electrical.QuasiStatic.Polyphase.Sources.FrequencySweepVoltageSource, but they are not identical.
Locally:
parameter Integer m=3 "Number of phases" annotation(Evaluate=true);
Inherited from Modelica.Electrical.QuasiStatic.Polyphase.Interfaces.TwoPlug which inherits it from Modelica.Electrical.QuasiStatic.Polyphase.Interfaces.TwoPlugElementary:
parameter Integer m(min=1) = 3 "Number of phases" annotation(Evaluate=true);
The specification requires that duplicate components are identical (MLS 3.4,, 5.6.1.4).