There is no way to translate this sensibly in English. "Is it eight or eight" has no meaning and certainly does not capture the intent of the Hebrew.
It was created for the learner to see the difference and be able to distinguish between gendered numbers. The translation is redundant, but that's not the purpose of this exercise.
The only sensible way of translating this question is "Is it eight masculine or eight feminine objects?" and it should be accepted. Otherwise, there is no point including the question in translation exercises.
You're right, in a sense.
But duolingo is a translation based system, so everything there is to teach is taught that way.
Depends on your device and system. It's not required for the course, though.