Doppelgangers are legendary creatures that are told to be the double spirits of people.
According to the belief, doppelgangers appear to have no reflections in mirrors nor do they cast shadows.
Seeing a doppelganger was considered a bad omen, ultimately revealing that the original will soon die or would suggest that something terrible will happen to them.
It is said that Abraham Lincoln saw his doppelganger and, after he revealed this fact to his wife, she told him that he would not live to serve his second term as the president of USA. Lincoln was killed right after he was chosen to be the president for a second term.
Also, John Dunne, the famous English poet said he saw the doppelganger of his wife when he was in Paris. He came back home to find out that his wife gave birth to a stillborn baby.