Pope Innocent II was in hiding for 8 years while Antipope Anacletus II was the visible "pope" (cf. this).
To remove the remnants and evil consequences of the schism, Innocent II called the Tenth Ecuмenical Council, the Second of the Lateran. It began its sessions on 4 April, 1139. One thousand bishops and other prelates are said to have been present. The official acts of Anacletus II were declared null and void, the bishops and priests ordained by him were with few exceptions deposed.
If this were to happen chaos would ensue. All the bishops and priests ordained by all the Popes since 1958 (61 years +) and their follow on bishops and priests would have to be hunted down and deposed.