Based on the equivalence principle and the reciprocity theorem, the problem of light scattering of plane wave/Gaussian beam from arbitrary two adjacent objects is considered and a solution that accounts for multiple scattering up to second-order is evaluated. In general, the first-order solution can easily be obtained. However, due to the difficulty in formulating the coupled scattering field, it is impossible to find an exact analytical solution for the second-order scattered field. In order to overcome this difficulty, the second-order solution of light scattering of plane wave/Gaussian beam from two adjacent conducting/dielectric objects is derived by employing the reciprocity theorem and this solution is simplified from volume integral to surface integral form by using the equivalence principle. In specific, the composite scattering field from two adjacent spheres is calculated. The bi-static scattering is discussed, and the results are compared with numerical computations based on time-domain integral equation method (TDIEM). Meanwhile, the dependence of the scattering section and the degree of polarization on the beam-waist radius and the locations of the objects are also discussed.