Original sentence: However, after its restoration in 2012, the Prado's Mona Lisa was claimed to be the earliest known studio copy of Leonardo's masterpiece.The Prado Mona Lisa is a painting of the same subject as Leonardo da Vinci's famous Mona Lisa, which is held by the Louvre Museum, Paris.The painting has been displayed in the Museo del Prado in Madrid, Spain since 1819, but was considered for decades a relatively unimportant copy
Edited sentence: However, after its restoration in 2012, the Prado's Mona Lisa was claimed to be the earliest replica of Leonardo's masterpiece.The Prado Mona Lisa is a painting of the same subject as Leonardo da Vinci's famous Mona Lisa (which is held by the Louvre Museum, Paris).The painting has been displayed in the Museo del Prado in Madrid (Spain) since 1819, but was considered for decades a worthless copy