Their singularity, from a pictorial point of view, is manifested in relation to the dynamic-luministic accentuation that is expressed in terms of material tenderness.
It should also be noted how a duality of intent is evident between the two pairs of panels, as a cadenced and almost static rhythm, appropriate to figures caught in ecstatic contemplation, as in the case of Saints John and Monica, is contrasted, in the scenes of the Martyrdom and the Baptism, by a compositional flair that involves the dynamics of the form through a flickering luministic effect.
Having accepted the hypothesis that the two panels were part of the same polyptych of Saint John and Saint Monica, from an executive point of view we must think of the intervention of a collaborator of the De Mio workshop.