HCR (149 pairs), and stellar 40-pair HCM and HCD subsamples. The HCR sample and comparison to a random bootstrap of 40 pairs (top left).The planet pairs (blue dots) around host stars with similar properties: around cool stars, T_eff ∈[2566; 4398] K (masses, bottom left), around those with [Fe/H] ∈[−0.210; −0.010] and old stars, age ∈[6.03; 12.3] Gyr (top and bottom right, densities). The grey dots represent one realisation of the bootstrapped 40-pair samples out of 10⁵ simulations. The red dots correspond to the Solar System planets. The black dashed line is the 1:1 line.