Orbital semimajor axes and eccentricities of surviving CoRoT-9b analogues from our numerical simulations. The blue planets are those that remained after the second planet was ejected; each vertical band corresponds to a specific mass for the extra planet. The green circles are simulations in which either there was no instability or the two planets collided. The measured orbit of CoRoT-9b is shown with the red symbol; the error bars are 1σ.