Oh no! You created the same project twice. Don't fret; delete!
Head to the project page. If you're in the editing interface already, hit the "Go to project" button.
Note the "Edit" button near the top of the page. Next to it, there is a button with three vertical dots ( ⋮ ).
Click that button and select "Delete this project"
Hit "OK" on the confirmation screen... if you really do want to delete it!
Use this power wisely, as we cannot resurrect a deleted project.