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 sometimes ordered in duplicate by our customers.
To warn us, you can go on the mission page and click on “Make changes or ask for help”
Then select “Other”
And give us as much information as possible :