Today I got an audit (which I passed because I tried to edit it - it throws a "has been deleted" error) of a seemingly good answer (I lost the link). The answer is good, however it has been removed because basically similar answer of an existing answer.
The review UI does not show existing answers, and I see a good reason for that. If I was in a good mood doing a very thorough review, I usually check the question if it has similar answer. But in my standard review, I only check if it is formatted well, if it answers the question, basically all checking that can be done within that one view - the answer against comments, the question, the formatting (in review queue).
If the UI itself does not expect users to check against other answers, is checking against existing answers the expected standard, or it should be left as "best practice" which does not necessarily to be done?