Aren't you admin?
Don't hesitate to regroup duplicates when you find them, I sometimes feel that I'm the only one to do that
(on "my" series I check from time to time for duplicates, but others don't seem to do it much)
Usually the one kept as main is the oldest, or the biggest role, but for the Volvo I'm not sure which one to set as main, as the background one has a much better pic than the one with a role