We argue theoretically that a new state. namely, no halogen displacements around Pd ions and, consequently, their trivalent states with finite magnitudes of spin, will be realized by modest inclusion of Ni ions in Pd-Ni mixed-metal MX-chains. This state is peculiar to such mixed-metal systems, because it is never found as a ground state for homo-metal chains of Pd. Moreover. from the theoretical viewpoint, strong electron-lattice interaction and strong electron-electrou Coulombic repulsion are mixed up to give a very interesting example for the study of both. Here we particularly discuss the following two points, based on Hartree-Fock (HF) calculations applied to a extended Peierls-Hubbard model. One is the dependence of the metal valencies on the mixing ratio. The obtained dependence is well consistent with the. IR spectra,, which shows the disappearance of charge disproportionation in the presence of 30%-Ni ions. Another theoretical result is on the relative position between the two metal bands. It has been assumed in the previous calculations that the two centers of the gravity of them were located at the same position. In this study, we show that the main conclusion survives even if they are apart from each other by a moderate energy.