Possibility to add several submissions to the leaderboard

Participants should be able to put several submissions on the leaderboard. For the COMETH project, I will submit several reference dataset and I want them to appear on the leaderboard (with meaningful names, see issue #538 (closed)) I thought a temporary solution would be to create as many user accounts as reference datasets, however, as creation of a new user account requires a unique email adress identifier, it is not an option.