A pair of identical twin brothers have both been charged with rape because their identical DNA means the attacker cannot be identified.
Mohammed and Aftab Asghar, 22, appeared in Reading crown court charged with the rape of a woman, despite only one of them allegedly being responsible.
Details of the sexual assault, which took place in November 2011, are not known, but it is thought only one of the brothers will stand trial. One of the twins is not believed to have been at the site of the attack.
Prosecutor Sandra Beck, who has requested more time to pursue certain lines of inquiry, said: "It is an unusual case. They are identical twins. The allegation is one of rape.
"There is further work due and there is an indication which would tend to support that one was not at the location. It may mean that only one of the defendants faces trial."
A trial date has been set for 2 December and both twins have been granted conditional bail.
Identical twins share the same DNA but have different fingertips because even in the space of the womb, the foetuses have contact with different parts of the environment, which results in skin variations.
Irish twin gets away with rape
This is not the first case of identical twins being charged for rape because their DNA was the same.
Earlier this year, 24-year-old twins Elwin and Yohan were arrested because one of them was believed to have raped six women aged between 22 and 76.
DNA evidence was found on the female victims but because the brothers had identical genes, police could not establish which was the attacker. The victims were also unable to tell them apart when asked to identify the rapist.
Another case from 2003 in Ireland led to a rapist being released without charge. According to the Irish Examiner, a woman was dragged to some waste ground as she was walking home in Limerick and was brutally raped.
Police said the victim could identify her attacker as one of a pair of identical twins, but could not tell which one had raped her.
Chief investigator Emmanual Kiehl said the DNA test could not distinguish between the two and despite there being strong evidence against one of the twins, the Director of Public Prosecutions ordered police to drop the case because the accused's brother would not cooperate with police.