strange sort order with sort=threads and sort_aux=reverse-score

[Louis-David Mitterrand]

In the .muttrc I have:

set sort=threads sort_aux=reverse-score

in order to get the highest rated messages at the end while still seeing
threads. However this has the unfortunate side effect that
identically-scored messages are more or less sorted from newest to
oldest (not the default date-sent).

Is there a solution to this?

TIA,

-- 
    PHEDRE: Pour bannir l'ennemi dont j'�tais idol�tre,
            J'affectai les chagrins d'une injuste mar�tre ;
                                          (Ph�dre, J-B Racine, acte 1, sc�ne 3)