When I looked at the Numista website forum today it appeared that the idea to have multiple pictures in a listing was rejected because two posts on the topic were now “Rejected”.
For people who strongly want multiple images that could have been depressing. And it is inaccurate – the idea wasn't rejected.
I suggest an alternative state, “Merged”, instead of rejected to use in this case. No operational difference from Rejected, but it has a different name and a different icon. (I suggest a curved arrow something like ⤷.)
For a little more effort, setting the Merged state could ask for the URL of the other discussion so the person closing the discussion could perform one operation instead of posting a message and then changing the state.