Light curves in the ZTF g, r, i filters along with the SALT2 fits overplotted for the SN Ia pair from the spec subsample with the largest difference in x₁, i.e. ZTF18abdmgab and ZTF20abqefja. As discussed in the text, the high Δx₁ and low Δc are important for constraining the width-luminosity relation. The difference in x₁ in the light curve shapes of the two SNe Ia can be seen as well as the time of the second maximum in the i-band and the r-band shoulder.