NEW YORK, NY (REUTERS).- A portrait once believed to have been painted by Leonardo da Vinci sold for more than $1.5 million in New York on Thursday, around treble the top price estimated ahead of the auction. Auction house Sotheby’s said another version of the portrait, “La Belle Ferronniere,” is in the Louvre in Paris and it is that painting that is now generally agreed to have been by da Vinci himself or one of his pupils, while the painting sold in New York was a later copy. The painting is thought to be of Lucrezia Crivelli who was a mistress of Ludovico Sforza, the Duke of Milan, and was painted sometime before 1750 by a follower of the Renaissance master. But for more than 80 years the identity of the artist was in dispute and the controversial work was the subject of a slander trial in the 1920s, as well as two