Yeah. It's obvious what you were thinking along the lines of...real life situations. But those don't apply here. It doesn't matter if it's a book or TV. Genres still apply whenever a story is being told. People who search for "mystery" books or films, are specifically searching for a "who done it" scenario where the crime is always solved by the end. And part of the fun is trying to figure out the answer...because you know there is one.

"Unsolved Mysteries" is telling crime stories that can't be solved and have no answer....which breaks away from everything "Mystery" as a genre, is defined by. Therefore "Unsolved Mysteries" is not redundant.