Integrated spectra of the N and S sources (left and right panels, respectively), targeting the [CII] line with a spectral resolution of 28 km s^-1 per channel. The spectra have been extracted from the ALMA data cubes using beam-sized apertures centered on the sources. All velocities are referred to a redshift z = 4.6949. The red curves denote the best fits, which are obtained with a double Gaussian function for both sources. For the QSO the width of the second component is fixed to that of the main component. For the SMG, the velocity of the fainter component is fixed at 250 km s^-1 (Salomé et al. 2012).