Translation:Go by yourself, I don't want to go!
I don't think that this is an inaccurate translation, but it's the answer I'm shown when I enter "You go. I don't want to go!"; "alone" is "一個人", which isn't in the sentence.
"你自己去" is literally "you self go" which would translate to "Go yourself." (Unfortunately, Duolingo requires "Go by yourself.")
In everyday speaking, that translation is fine. But the Chinese sentence itself does repeat the verb 去 - and thus, so should you. In my experience, if you want to have the best chance of getting a correct answer from Duo, it's best to try to stick as close to the meaning of the original sentence as possible, without sounding stilted. (Although, as we have all seen, that doesn't always work out in Duolingo, especially with Chinese!)