A doppelganger is said to be the double or a ghostly apparition of a living person. Sometimes a doppelganger may be seen in one location when it is known the person was actually in another location. Other times, the doppelganger may be seen with the person, as was known to have happened in the case of a 19th century teacher named Emilie Sagée.
It is said that one day, while teaching a class, Sagée's double appeared right next to her and mimicked her every move as she wrote on the chalkboard in full view of 13 students. Although others could see the double, Sagee never noticed the double nor did she notice that own movements slowed when the double appeared.
Sagée's double also appeared away from her though. In another instance, the entire student body of 42 girls assembled in the school hall for their sewing and embroidery lessons. The double appeared in Sagée's chair while Sagée could be seen outside in the garden. Two of the girls attempted to touch the phantom Sagée but felt an odd resistance to her. One of the girls stepped between the chair and table and passed right through the phantom, which remained motionless and then disappeared.
It was said that Sagée's double would appear when she was worried or immersed in her work. It was said the double could also appear in a place Sagée was thinking about, like in the case above where she was in the garden; she looked inside at her chair and thought to herself that without supervision, the students may waste time and gossip.
So what was Emilie Sagée's double? A piece of her spirit leaving her body and traveling on it's own? Or just some kind of projection she gave off without even knowing it? The bigger question may be did it really happen at all? The sources I looked at said the tale was written by Robert Dale Owen who heard the story from Julie von Güldenstubbe, a student at the school Emilie Sagée taught at. Although it was said that her double was witnessed by multiple witnesses on more than one occasion, the sources don't indicate the story was actually corroborated by multiple witnesses. It would be nice if others had come forward with the same story. Without multiple witness corroboration, you have to wonder if the story was true at all.