In cases like this, a duplicate has most likely been created by mistake.
It happens (very rarely) that another image creator has visited the scene before you and / or accepted the mission before you.
We do as much as we can to identify and anticipate this error but some missions are ordered in duplicate by our customers.
To help us find this type of incident, please change the status of the mission to "Customer Refusal" and leave a comment on the mission page. In the drop-down menu, select "I want to report a duplicate" and write your comment.
Don't hesitate to contact us for more details if necessary.