“Other, specifically Duplicate: We cannot add your theme to the gallery because we do not permit duplicate copies of existing themes. We appreciate your involvement in the Theme developer community.”
I submitted a theme named “True Dark Mode Opera W10”, but it was rejected during to being a duplicate (?) - which is false, there are similiar themes, but none like mine, and I checked out all of them I could find, none of which matched my theme 1:1.
The rejection message should have included instructions on how to appeal the decision.