Premise: In ancient Roman religion, Antevorta was a goddess of the future, also known as Porrima. She and her sister Postverta (or Postvorta) were described as companions or siblings of the goddess Carmenta, sometimes referred to as "the Carmentae". They may have originally been two aspects of Carmenta, namely those of her knowledge of the future and the past (compare the two-faced Janus).
Hypothesis: Antevorta and Postverta were twins.