The calculated dipole moment and polarizability of a molecule are affected by the position of the ghost orbitais of its partner subunit within a molecular complex. The IR and Raman intensities, evaluated in terms of the derivatives of these properties with respect to an intermolecular motion, are hence subject to a secondary basis-set superposition error (BSSE), here calculated for (HF)2 with a variety of basis sets. Whereas the IR intensity is only slightly affected, the BSSE introduces enormous errors into the Raman intensities. These errors can be reduced if two sets of polarization functions are included in the basis set.