Merely placing two compact objects near each other in orbit is not the appropriate way to design initial conditions. In nature, these two stars have felt each other’s gravitational pull for quite some time before the last few orbits (where the merger happens). And so, they should be tidally distorted and not overflowing their Roche lobes at the start of the simulation. I’ve spent a few years now perfecting the generation of initial conditions for white dwarf mergers, and I think this image demonstrates best how accurate they are.