This here is the second ever binary stellar remnant I have found so far. It is a neutron star and an accreting white dwarf. I assume that binary dead stars are rare in SE, and I would be interested in seeing or finding other multiple combinations of WDs. Qs an Xs. (RSC 8474-314-4-2259-11)
RS objects do not appear in the search box. But if the star exists, you can still go to it with 'Go to'. If the star does not exist then not. For example, if the RS number comes from another SE version. Or certain addons are used.