  We investigate the influence of the chemical potential mismatch $\Delta$
(different electron densities) on Coulomb drag between two parallel ballistic
quantum wires. For pair collisions, the drag resistivity $\rho_{\rm D}(\Delta)$
shows a peculiar anomaly at $\Delta=0$ with $\rho_{\rm D}$ being finite at
$\Delta=0$ and vanishing at any nonzero $\Delta$. The "bodyless" resonance in
$\rho_{\rm D}(\Delta)$ at zero $\Delta$ is only broadened by processes of
multi-particle scattering. We analyze Coulomb drag for finite $\Delta$ in the
presence of both two- and three-particle scattering within the kinetic equation
framework, focusing on a Fokker-Planck picture of the interaction-induced
diffusion in momentum space of the double-wire system. We describe the
dependence of $\rho_{\rm D}$ on $\Delta$ for both weak and strong intrawire
equilibration due to three-particle scattering.
