The article focuses primarily on the panel representing 'Luca Pacioli and Guidubaldo da Montefeltro', housed in the Museo Nazionale di Capodimonte in Naples. Critics have raised a number of doubts about the authorship of this painting, the discussion of which in artistic literature is relatively recent, having begun when the work was purchased by the Neapolitan museum after attention was drawn to it by Adolfo Venturi. The illustrious art scholar, in making it known in 1903, attributed the work to Jacopo de' Barbari, on the basis of an interpretation of the abbreviated Latin signature on the scroll resting on Pacioli's work desk, an interpretation he himself would go back on just a few years later. Despite Venturi's change of mind, most scholars have continued to include the 'double portrait' in the oeuvre of the Venetian artist who was a friend of Durer, even if this attribution is objectively at odds with the style of the painting. Here we seek to reappraise the cultural aspects of the painting, without being conditioned by the presence of the signature, pointing out the clear similarities that emerge with the painting of Antonello da Messina during the years of his stay in Venice, Giovanni Bellini and Vittore Carpaccio. Starting precisely from this observation, we propose that the panel in question is the work of that “Venetian Jacometto”, an artist living at the end of the 15th century about whom Marcantonio Michiel spoke with admiration even in the fourth decade of the following century. We are referring to a painter and miniaturist who was sensitive to Flemish culture, but was above all a true 'creation' of Antonello da Messina, who worked as a portraitist for the Venetian aristocracy and for various illustrious literati of the Serenissima like Bernardo Bembo. The career of Jacometto, about whom there is little to glean from the scanty documentary evidence, must have begun around 1475 and ended about twenty years later, certainly before 1497, the year the artist had already been dead for some time. The inclusion of the 'double portrait' of Capodimonte among the works of Jacometto allows us to reappraise the artist's production in its entirety, giving the internal chronology of his paintings a greater degree of consistency. It is further proposed to attribute to this master the panel painted on two sides with the 'Portrait of a Young Man' of the Louvre – usually referred to rather generically as by some painter active in Venice at the beginning of the 16th century – which closely compares with the 'Portrait of Luca Pacioli and Guidubaldo da Montefeltro', but also with the style characterizing the more Antonellian works of this great and rather elusive Venetian portraitist.