From the Catholic Encyclopedia:
At least three different Saint Valentines, all of them martyrs, are mentioned in the early martyrologies under date of 14 February. One is described as a priest at Rome, another as bishop of Interamna (modern Terni), and these two seem both to have suffered in the second half of the third century and to have been buried on the Flaminian Way, but at different distances from the city. In William of Malmesbury's time what was known to the ancients as the Flaminian Gate of Rome and is now the Porta del Popolo, was called the Gate of St. Valentine. The name seems to have been taken from a small church dedicated to the saint which was in the immediate neighborhood. Of both these St. Valentines some sort of Acta are preserved but they are of relatively late date and of no historical value. Of the third Saint Valentine, who suffered in Africa with a number of companions, nothing further is known.
From a Carmelite community in Ireland:
The Roman Martyrology commemorates two martyrs named Valentine (or Valentinus) on February 14 which seems to indicate that both were beheaded on the Flaminian Way, one at Rome the other at Terni which is some 60 miles from Rome. Valentine of Rome was a priest who is said to have died about 269 during the persecution of Claudius the Goth (or Claudius II Gothicus). The other Valentine was allegedly Bishop of Terni, and his death is attested to in the Martyrology of St Jerome. Whether there were actually one or two Valentines is disputed. One possibility is that is two cults – one based in Rome, the other in Terni – may have sprung up to the same martyr but that in the mists of time his true identity became confused. . . .Under the rule of Emperor Claudius II, Rome was involved in many bloody and unpopular campaigns. Claudius the Cruel was having a difficult time getting soldiers to join his military leagues. He believed that the reason was that roman men did not want to leave their loves or families. As a result, Claudius cancell