Hmm.. Xavier, do you consider it to be an error and even a bad idea?
the "core" of the challenge (as I see it) is a) participance with your photo; b) voting for others entries -- to choose collectively the finalists. this is the core part and the main, basic idea. the details are not crycial and may vary. if you will drop here in comment section A Link to your post - that would be an error, but dropping a certain picture from your post + the link to your post is totally ok. the post may contain 5, 10, 20 pictures, only one take part in the contest. that is a basic and pretty standart practise... nothing special. wish you well!