According to a small article I wrote in the articles section of our coven, http://www.spellsofmagic.com/coven_ritual.html?ritual=3159&coven=595 a doppeleganger is below noted. I don't know anything about what dancerakm is speaking about though.
Informational article about Body doubles, bilocation, doppelganger, fetch, double walker, and the astral body
Body double is also known as bilocation, doppelganger, fetch, double walker, and the astral body. The double is often seen as an apparition and is suppose to be an exact image of a person. How exactly this phenomena occurs, is unknown though there are some theories. One theory is that it is a person astral body which is likely especially if one is in bed and witnessed elsewhere.
Some legends hold that seeing your spirit is an omen of your impending death.
According to some legends, if a person wishes to know whom will pass from this world into the next in the year to come, one must stand at the door of a church at midnight on the eve of St Mark (24, April ). Legend has it, all doubles from those that are about to pass will enter into the church in a somber precession. Should the onlookers see their own double, it?s a sign that they themselves will parish from this world in the coming year.
Reported cases or sightings
There have been reports of people seeing their own body or the doubles of others over the centuries, though not all have crossed from this world to the next. A German Poet named Goethe, whom lived 1749-1832 is said to have viewed his own apparition walking up a garden path toward him. According to the European myth, this should have meant Goethe would pass immediately, but it?s said, Goethe lived well over a year after viewing the image. It is said that Emilie Sagee, a French school teacher, was witnessed in two different places at the same time by her students in 1845. A young teen from England named Lucy Eden was said to have been witnessed in two places at once by her peers in 1845. Oddly enough, in 1847 when Lucy was in bed ill with the mumps, she was again witnessed in other places in the home speaking with friends, relatives and maids.
People said to be good with Bilocation
At this time, the only valid account of a person performing bilocation is Saint Martin de Porres is said to have performed the ?miracle? of bilocation.