i acidentally requested the same run twice and i want to take it down

Find your Pending Actions page (click on the hourglass at the top then "View All", or find it on your profile) You can click on one of the duplicate runs to view it in there. From that page, there should be an option to remove the run. You can also wait for a moderator to accept/reject it.

Hope this helps :)

You can't remove a run unless your account is at least 1 week old but don't worry cuz the mod can do it for you. As for the reason why, don't ask me cuz I can't tell you