Is it not in Ukrainian still correct to add an extra I? Я іду кудись я не знаю куди
It's a small point, but the English sentence isn't grammatical. "I am going somewhere, I do not know where" is a comma splice. The comma should be replaced with a period, or a coordinating conjunction should be added (e.g. "but"). I've reported it.
This is common and fine, and has nothing to do with grammar in any case.
Doesn't it need another ya after the comma?
Why is Я їде кудись я не знаю куди marked incorrect?