That is an interesting observation. Duolingo generally likes us to mark only "one translation" as the best. There is a good justification for this for most languages. We have tried to be gender neutral in the sense that we have tried to provide feminine versions as the "best" translation on some and the masculine version for others (actually you may find more of these overall).
We might revisit this to see if we should mark both the masculine and feminine forms as equally best for the sentences where it applies.