The double ouroboros is an ancient symbol distinct from that of the single ouroboros. A single ouroboros is a circle formed by a serpent, often a snake, consuming its own tail. A double ouroboros is a more complicated symbol formed by a pair of twisted serpents consuming one another's tails.
The symbol was used by the secretive ancient alchemists. Some alchemists used it to symbolize alchemical volatility.
Following the popularity of the 1984 movie it became a popular symbol requested by clients seeking tattoos.