Left panel: XMM-Newton (left) and Chandra (right) images of SPT-CLJ 2146-4632 (top) and SPT-CLJ 0546-5345 (bottom) in the [0.3−2] keV band. The images pixel size is 2″, and for ease of comparison, the same scale is used for all. The magenta circle identifies the point source that contaminates the substructure emission in the XMM-Newton image of SPT-CLJ 2146-4632. Right panel: centroid shift parameter, ⟨ w ⟩, values computed using Chandra and XMM-Newton in units of 10^-2R₅₀₀. The dashed line is the identity relation. The two dot-dashed lines define the region where the clusters are considered to be dynamically relaxed (see text).