Double Quickenings are exceedingly rare, they occur when at least four immortals are engaged in combat and two vanquish their opponents at very similar or the same time. The Quickenings of the slain immortals appear to commingle before joining the victors. Double Quickenings are apparently more destructive and powerful than a normal Quickening, though it is hard to say for certain as the only confirmed Double Quickening involved the deaths of two extremely ancient immortals whose Quickenings would have been quite powerful in the first place.
Another possible Double Quickening occurred in 2008 between Amanda Darieux and Methos after they vanquished two unknown immortals on a beach near Amanda's home. While Watcher Joe Dawson was present he was retired from the organization at the time and it is not known whether he has recorded any confirmation, additionally there is no record from Amanda or Methos' Watchers, assuming they were active and observing at the time.The rarity of Double Quickenings is due to the small number of active immortals and the usual penchant for immortals to avoid other immortals outside of any friends they may have, friends who are unlikely to issue a challenge. It is interesting to note that the notoriously elusive and difficult to pin down ancient immortal Methos has been involved in at least one and possibly two of these ultra rare occurrences.