Most Atoms have only one core but it is hyperthreaded, so they behave as a dual core, except that they are muuuuch slower.

Repair job is a group term for work that is send from the servers in replacement of tasks that broke, had no reply, were invalid, were aborted on host. Repair jobs are only circulated to known reliable and quick returning devices. They have a much shorter deadline, which is what makes them fairly easily recognizable. Details are described in the Start Here FAQ's in topics such a Deadlines.