A dictionary says wrong means not right, then does there's no wrong answer have a double negative?
The type of double negative that is unacceptable in standard English is the type where the two negations reinforce each other or reflect each other or agree with each other (instead of contradicting each other).
So, you shouldn't say "I haven't got nothing" (unless you mean "I have got something").
There is nothing wrong with having two negatives in a sentence if you are using them correctly to cancel each other out. If you're using "It's not nothing" to mean "at least it's something", that's correct English. If you're using "I'm not doing nothing" to insist that you are in fact doing something, that's correct English.
So, even if you were to regard "wrong" as a negative (which is dubious - the notion of double negation usually refers to negators such as "not", "nothing", "never", "nowhere", etc), there would still be absolutely nothing wrong with saying "It isn't wrong" (which has a slightly different shade of meaning from "It is right" - because being "not wrong" includes the possibility of being neither wrong nor right).