Velocities of every peak and trough for the double-peaked galaxies having a systemic redshift (Sect. 5.3). Each line corresponds to a source, where the blue (red) circle shows the bluer (redder) peak and the green square indicates the position of the trough. The larger circle represents the peak with the highest flux. The first line of the bottom part of the figure shows the mean positions of the trough and the blue and red peaks of the objects shown above (without taking into account ID 263). The mean LBG and mean Green Pea (GP) are drawn from the literature, Kulas et al. (2012) and Orlitová et al. (2018), respectively.