Although the lighter colour from the Exhibition duo looks similar to Prance in the pan, I think you will see it is quite a bit darker and more mauve when swatched. Unflappable appears more brown when compared to the dark plum of the Exhibition duo.
I think that in the picture above Prance looks quite similar to the lighter shade in the NARS Melusine duo. In the interest of checking that I really didn't have a dupe, I went back and did some heavier swatches and compared the pans.
|Left - Prance, Right - Melusine|