Base-difference images of the white-light signatures generated in the low corona by the two combined CMEs forming the eruption discussed in this manuscript, marked as CMEa (magenta arrow) and CMEb (yellow arrow), as seen by SOHO LASCO C2 and STEREO COR2 instruments. The cyan arrow indicates a shock front associated with the eruption. A freely propagating shock, marked as Shock*, is propagating above the western limb in the instruments’ field of view, as is indicated by the orange arrow.