Python Application Sometimes Processes the Same Background Job More Than Once

I am working on a Python application that processes background jobs submitted by users, and I am experiencing one specific problem where the same job is occasionally processed more than once even though each job should only be executed a single time. Under normal circumstances, a job is added to the application’s queue, a worker picks it up, performs the required Python function, and then marks the job as completed. Most of the time this workflow behaves exactly as expected, but occasionally I c...