Two conducting spheres carry equal magnitude of charges. The distance between the spheres cannot be considered large in comparison with the diameters of the sphere. Then, (Neglect forces other than electrostatic forces)

Due to induction charges on the spheres will not be evenly distributed over the surface.

 In case of like charges, the sections of the sphere that are farthest from each other will have greater charge density, while in the case of unlike charges the sections of the sphere that are closest to each other will have an enhanced charge density. 

For this reason, the distance between the centers of charge for like charges is greater than that for unlike charges. Hence the attractive force between the unlike charges will be greater than the repulsive force between the like charges.