An approximate method is presented to calculate the full width at half maximum(F WHM) of photovoltaic(PV) spatial solitons(PVSSs) with twowavelengths component . An advanced numerical analysis i ndicates that two coaxial hyperbolic secant beams, provided that they satisfy th e functional relations of FWHM with amplitudes of this type of PVSS, will be ver y close to solitons when they propagate in PV crystals. Besides, this type of PV S S tends to be stable against small axial perturbations and small refractive inde x perturbations due to variations of temperature of the crystal. However, if the pro files of intensity of two coaxial signal beams with different wavelengths diff e r mildly from those of PVSS, the two beams will tend to experience cycles of co mpression and expansion; and if the profiles of intensity of the signal beams di ffer significantly from those of PVSS, these two signal beams will diffuse endle ssly.