It just came to my attention that when flagging (not VTC) a Question as duplicate one is presented with the following options:
As we can see, among those is the "a duplicate..." option. However, if we select the "should be closed..." option instead, we are presented again with an option to flag as duplicate:
I wonder what is the reason for the redundancy in that specific option? Are users more prone to select "should be closed..." instead and thus justify including the option there as well?