Baryonic Tully–Fisher relation twins “paradox”. Rotation curves of three pairs of galaxies with L18a parameters, each pair having very similar asymptotic circular velocities, but very different velocities at 2 kpc from the centre. The black dots with error bars are the observed rotation curves of each galaxy; the green dotted curves are the baryonic contribution to the rotation curves; the violet dot-dashed curves are the rotation curves of the DM halo; and the red solid curves are the resulting best fit rotation curves to the observed data.