Translation:I speak both English and Russian.
Sorry for this question but, is it necessary to put и twice or could I also say ''Я говорю по-английски и по-русски.''?
И before both exactly means "both". "Я говорю по-английски и по-русски" would be just "I speak English and Russian".
Sentences like this remind me of that moment in The Blues Brothers where John Belushi walks up to the barlady and asks what kind of music they do at Bob's Country Bunker, and she goes "We do both kinds: country AND western!"
Only there is a difference between English and Russian.
There is a и before both по-английски and по-руски, so the word "both" must be included for the answer to be correct
I put " Russian " before " English ", but Duolingo corrected me and told me my answer was wrong.
That's quite a free translation, which is not necessarily helpful in a teaching context. One could argue that it's implied in the Russian, but я могу doesn't actually appear in the sentence. In this context, a slightly more literal translation is IMO more helpful to the learner.
OK as a teacher myself I can accept that, but if a student wrote it I would not feel I could mark it down.
Both seems to me correct as и means "and" not IN. Si your correction does not seem right.