According to wiki:
Double ganger or commonly known as DOPPELGANGER is the ghostly double of a living person, a sinister form of bilocation. In the vernacular, the word "doppelgänger" has come to refer (as in German) to any double or look-alike of a person. The word is also used to describe the sensation of having glimpsed at oneself in peripheral vision, in a position where there is no chance that it could have been a reflection. They are generally regarded as harbingers of bad luck. In some traditions, a doppelgänger seen by a person's friends or relatives portends illness or danger, while seeing one's own doppelgänger is an omen of death. In Norse mythology, a vardøger is a ghostly double who precedes a living person and is seen performing their actions in advance.