Very few altarpieces of Flemish origin display free-standing, non-original figures along their lateral sections instead of more traditional narrative reliefs such as may be seen in the altarpiece of Las Navas in Pamplona and this example.
This altarpiece is even more unusual inasmuch as the figure of Saint Anton, an extraneous saint to the College of Apostles (complete with flames and a pig at his feet), forms part of the group and stands alongside the figures of two barefooted people holding books. These figures, which are similar to figures found on an apostolate originally from Brussels, have helped us identify them as Saint Peter (with a short, curly beard) and Saint Paul (whose hair is longer and wavier).
Extraneous to the original iconographic whole is the duplicated figure of Saint Anton and that of Saint James (Santiago) which, apart from having been executed in a completely-different style, had to be reduced in size in order to fit into the available space. The figure we can see today might well have replaced a figure of Christ the Saviour and been considered more appropriate. Whatever the explanation might be, this altarpiece was probably a specially-commissioned piece.