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White light is a wavefront with power(energy) equally distributed across the visible frequency spectrum. When the wavefront has power levels distributed at different frequencies so that some parts the spectrum have more or less power, then we call that a color. The wavefront that impacts the eye to produce the sensation of Magenta has high power levels in the lower and higher frequencies and low power levels in the center frequencies. It is just one wavefront but shaped in power intensity vs frequency. There is no such thing as different colors of light waves, only a wavefront that has a power vs frequency shape. As such there are not incoming different frequencies of light to produce a color, its just one wavefront. No separate blue or red light enters the eye to be combined and produce a color. The color is inherent in the energy distribution of the wavefront which stimulates the frequency sensitive biological receptors in proportion to the power levels within the wavefront.

It is for this reason that Magenta is (as are all colors) spectral. It is the energy vs frequency distribution of the incoming wavefront that produces the perceived color sensation. Any color you like can be produced by a single tunable light source through modulation.

One wavefront .... not seperate incoming light colors.