UndoChiralSplittings is an option of FCPrepareFAAmp. When set to True, it attempts to undo splittings of couplings into left and right handed pieces, e.g. a P_L \gamma^\mu + a P_R \gamma^\mu will be replaced by a \gamma^\mu.
UndoChiralSplittings
FCPrepareFAAmp
True
Overview, FCPrepareFAAmp.