goblinaerii:

Doubles are similar to familiars in the sense that they can be sent out from a witch in order to do a witch’s bidding. The key difference is that a familiar spirit is an entity separate from the witch themselves, whereas a Double is an extension of the witch’s physical self, of and belonging to themselves. Doubles often appear in an animal form, or a duplicate of themselves appearing lesser in substance. The Double is also referred to as the “second skin” or “daimon self”. Though they can be similar, the Double should not be confused with the fetch-beast. In Eva Pocs’ book “Between the Living and the Dead”, she describes how the the Double of a person is believed to possess substance: “According to the documentation, the alter ego is imagined to be a physical reality. This means that it was not a soul but a second body; and while it was of a more spiritual nature, it also had physical reality.”

The Double is often given to the witch by a spirit, such as in the case of the gift of an animal form that the witch could project themselves into and proceed forth. One can project a Double in much the same fashion as one can project a fetch-beast. 

*source material referenced: “A Deed Without a Name: Unearthing the Legacy of Traditional Witchcraft” by Lee Morgan and “Between the Living and the Dead” by Eva Pocs.