Long-slit spectroscopy of double-type candidates performed using EFOSC2 on the ESO/NTT or ALFOSC on the Nordic Optical Telescope. The candidates are arranged in ascending order of right ascension, with lenses or quasar pairs written in bold and stars or projected quasars in grey. The shaded regions indicate wavelength ranges that are affected by atmospheric absorption. The spectra were reliably deblended using the procedure outlined in Sect. 4.1. The flux ratios of the quasar pairs can be found in Fig. C.1.