Simulated Voigt profiles for single and double absorption lines in brown color. The green lines show the absorption lines after convolving with the HST’s tabulated LSF. The red dashed line shows the absorption line after adding the Gaussian noise and rebinning it to a similar velocity frame to the HST data. This red dashed line represents the typical absorption line used as the training dataset in this study. Left panel: brown line shows the simulated Voigt profiles for a single absorption line with N_HI = 10¹⁴ cm⁻², b = 80 km s⁻¹ and S/N = 25. Right panel: same as the left panel but a simulated double absorption line. The dashed lines show two simulated single absorption lines (N_HI = 10^14.29 and 10^15.06 cm⁻², b = 92.67 and 25.43 km s⁻¹) that are shifted by ±Δv/2 ∼ 75 km s⁻¹ value and the combined profile is shown in brown color. The training dataset for double absorption lines is shown in red dashed lines.