We numerically investigate the deflection characteristics of incoherent coupled bright and dark photovoltaic spatial soliton pairs in a photovoltaic photorefractive crystal with diffusion effect. The numerical results show that, owing to the incoherent interaction, a bright soliton and a dark soliton in the crystal trap each other and the centers of the two solitons move along the same trajectory. It is found that, the deflection of the bright soliton can be controlled by adjusting the input background intensity of the dark soliton when the input peak intensity of the bright soliton is fixed; and the deflection of the bright soliton is suppressed when the input background intensity of the dark soliton is at a special value, while the bright soliton undergoes a deflection when the input background intensity of the dark soliton deviates from this special value. Also, the deflection of the dark soliton can be controlled by adjusting the input peak intensity of the bright soliton when the input background intensity of the dark soliton is fixed.