The two women were born in the city of Las Palmas, in the Canary Islands, in 1973 and separated when staff mistakenly handed over a different baby girl, born about at the same time, to the parents.
The girls were brought up in the mistaken belief they were twin sisters, while the real twin only found out she had an identical sister at the age of 28 during a shopping trip.
A sales assistant in a clothes shop in Las Palmas, who happened to be a friend of the other twin, was taken aback after the woman acted as if she did not know her. She later realized she was dealing with twins, and arranged for the two women to meet.
"It was like looking in the mirror," said one of the sisters, who want to remain anonymous. "They walked the same, looked the same and spoke the same," a lawyer said.
The women started investigating the circumstances surrounding their birth, and a DNA test later proved that one of the identical twins had been accidentally exchanged for another baby soon after birth.
A decision in the case, which has been working its way through the Spanish courts since 2004, is expected soon.
All of the women are demanding compensation from the health service for psychological damage. However, media reports said the hospital has offered only 700 euros ($1,000).
