From the report, it seems that you are working an a web farm environment, and that the (I assume it is) scheduled task is running on both servers, so each one is trying to create the same file. You don't want that task to run twice.
It's been a while, but I think that you need to limit that scheduled task to one of the servers. You do this by going to the Persona Bar's Scheduler page, go to the Scheduler tab and edit the Site Import/Export task. There is an entry for Servers.
I would also follow Michael's advice to restart the AppPool. And, I'd also go and delete the failed export file.