From the statement above, I will assume the following. The most likely situation of seeing a double image reflection of a person is in a dressing room in one of the clothing shops where one tries on some new clothes standing in front of a three-way mirror, i.e., a full mirror in front and a full mirror on the left side and a full mirror on the right side. That front mirror gives the person a frontal transposed view, the left and right mirrors would give one a double image reflection of the same person.
Another possible situation is a frontal double image of a person, as if the same person is standing simultaneously in front of the right eye and in front of the left eye and each eye is seeing an image of the same person. If one shows the same image on two TV screens and stares at the middle in between the two screens, one sees a reflection of the image in peripheral vision of both eyes simultaneously.
Interpretation of seeing a double image reflection of the same person might be something like this: The double image may be the images of one’s auras, as Balzac said: “Every body in its natural state is made up of a series of ghostly images superimposed in layers to infinity.”
Seeing many images of oneself in dreams is not that rare. There have been dreams where one sees oneself in one place in a dream and turns and sees oneself also in another place as if simultaneously. The new theory of the photon being at two places at the same time illustrates this point.
If one subscribes to the theory of parallel universes, the dreamer in the dream may be seeing oneself in two parallel universes or two parallel worlds.
Now if the dreamer is seeing a double image reflection of another person than the dreamer himself or herself, it reflects one’s ability to see auras. Many people can see auras of other persons. In my meditation classes, many of my students were gifted in psychic abilities and in Reiki. Some could see several layers of one’s “auric” layers and many Chinese medicine practitioners can “see” a patient’s energy fields. They can also describe the energy fields and tell the difference between a person who is healthy and full of energy and a sickly patient who lacks energy. Healthy organs emit strong auras and energy fields while unhealthy organs emit weak auras of unhealthy color and weak energy fields.