I've got an warning and a temporal ban when reported some duplicated images. The message warned me that the ban is temporal (1 week?) I'm not sure.
However I'm still not able to report these two for example: https://wallhaven.cc/w/135wzg https://wallhaven.cc/w/dgrv2o
The message in the UI is: "Something when wrong. Sorry :/"
P.S. The wording of the message before the ban was not easy to understand for me. Adding some URL to explanation in the forums will be better. The message is for the case when it can't be determined which image is the good (not upscaled and processed in other ways).