Comparison between SPEXXY and ULySS. Left: Velocity differences for pair measurements obtained with the two codes. The solid black line represents the zero velocity offset. Filled circles are colour-coded according to their S/N_C, while the grey error-bars indicate the combined uncertainty, that is $\sqrt{{\delta }_{\mathrm{rad},\mathrm{Spexxy}}^2+{\delta }_{\mathrm{rad},\mathrm{ULySS}}^2}$. Right: Direct comparison between the effective temperature values obtained with the two codes; the solid black line is for reference only.