I have two friends (a male and a female) that they say that they have a twin - a black being, like a shadow that guards them.. They have different cases.. My female friend said that when someone sleeps in their house, especially for the first time, they notice someone who's like roaming around in the bedroom, even when they sleep with my friend.. Once, my friend said to her bestfriend to just ignore it because it will really scare her if she will still look at it.. My other friend's case is different.. When his friends came to his family's house and after the end of the party that night, they decided to sleep in his bedroom upstairs. My friend will just sleep in the sofa downstairs. Upon his friends enter his room, they saw a black shadow in his bedroom. They were all scared and went downstairs to tell it to my friend.. My friend accompanied them upstairs to see what his friends are talking about.. Immediately, he showed his uncle sleeping in the next room to see if his uncle is whom they are talking about, but his friends said that it is not his uncle whom they saw so he thought and after a while, he said to just ignore that shadow.. He said about the black shadow which they are talking about is his twin.. He further explained that his parents noticed a shadow in his room when my friend was still a kid.. Then they realized that it could be his twin because they are the same in height until he grew up.. Can you explain me what is this? What is this called? Is this true or just a make-believe?