Data for four dual quasars, verified using publicly available spectral datasets. On the left, we provide essential details: Δv represents the velocity difference, ‘sep’ denotes the image separation of the two quasars, and ‘dis’ indicates the projected separation in the line-of-sight direction at lower redshift. The second column displays the spectra, where the fluxes have been smoothed using a Gaussian kernel with a standard deviation of 5 Å. The third column features the grz colour image from the DESI-LS DR10, while the final column shows the residual image derived from DESI-LS DR10.