I looked up Valentine on the saints calendar, and I found that there's two of them with a February 14 memorial. Well, maybe two. Valentine of Rome and Valentine of Terni may be different people. But depending on which account you read, either "most scholars" or "some scholars" think these two Valentines are the same person.
Their dates vary by about 95 years, and Terni is 64 miles from Rome, but they suffered very similar gruesome deaths. Valentine of Rome was "beaten and beheaded," while Valentine of Terni was "imprisoned, tortured, and beheaded." Ouch. Those ancient Romans give new meaning to the expression "love hurts."
I suppose we'll never know for sure if one or two Valentines brought us the romantic holiday that has endured through the centuries, but it really doesn't matter. Like true love, Valentine's Day is forever.