[en] Double differential nuclear cross-sections measurements (neutron energy-emission angle) usually rely on biparametric counting histograms. Alternatively the detector output may be processed on-line to produce the angular distribution as an expansion in Legendre polynomials of cosθ. The Legendre moments are accumulated in a set of single parameter histograms covering the neutron input energy range so they may be visualized during acquisition. Their covariances are accumulated simultaneously in another set of histograms. The multiple weighted counting method producing these data is presented and discussed in comparison with the classical off-line least-squares analysis of biparametric counting spectra