I am solving the algorithm problem Valid Anagram. The official answer judges that "hello" is a valid anagram of "hello". I am doubting this test is wrong.
The usual definition of anagram is:
A word, phrase, or name formed by rearranging the letters of another, such as spar, formed from rasp.
In the trivial case where you have the same arrangement, it's not another word. Similarly, we don't consider words to be synonyms or homonyms of themselves -- these terms are only used when referring to different words.
The website you link to won't let me see the solution (I guess I have to sign up). I expect that it doesn't really match the real definition, it just tests whether two strings consist of the same characters. In particular, I'll bet it doesn't actually test whether the inputs are real words.