I found a system with 3 WWs today, 2 of which were orbiting each other, and only 1 had an atmosphere (it was the one orbiting the other). Very odd combination...none were terraformable, and the system map really screwed with my head because I've never seen a WW look like that before (looked like a blue-grey HMC). Same system had 3 T Tauri "Neutron" stars as well...tiny little things, but without all the neutron star dangers.