"On se connaît ?"

Translation: Do we know each other?

[lizfindl]

Do we know one another is the same as the answer shown above. Why is it wrong?

[johndelaroo]

I am not a native speaker, but it seems to me that you are not wrong, but maybe you have not reported it, and maybe Duo has not fixed it yet, and Duo takes a very long time to fix some sentences.
Another possible way to say "one another" = "les uns les autres".

[trikkilee]

Could this also mean "Do YOU know each other?"?

[johndelaroo]

Ce serait sûrement mieux: vous vous connaissez?