Say you are studying colors. You are shown an image of "aquamarine", you think it's it cyan, so you type in "cyan" as your answer. This is wrong, but in what way is it wrong? Is cyan lighter or darker than aquamarine, is it too green or too blue? With this addon, if your guessed answer, "cyan" in this case, matches some other card you will be shown that card's front for easy comparison. In this case you will be shown cyan and aquamarine and can see that aquamarine a bit more greenish than cyan.
I only tested it for colors in this deck https://ankiweb.net/shared/info/661303954, but it should work for other decks if they follow a similar structure.
You can find the repo here https://github.com/Tim2othy/anki-show-wrong-answer.