A320 Dispatcher is informed by Captain enroute that the MEL applied to the #2 center tank pump should have been applied to the #1 pump. Flight continues to destination.

Narrative

Flight was dispatched with #2 center tank pump inoperative; with 6500 LBS in center tank at departure. Approximately 30 minutes after takeoff; Captain requested a voice patch with Maintenance and told them that he believed the wrong center pump was deferred after not getting proper fuel flow from the #1 center pump while in 'Auto Fuel Feed.' Captain came to this conclusion by turning the center fuel feed to 'manual' and turning on the deferred #2 pump. In this state; fuel flow from the center tank was restored normal. Maintenance agreed that the MEL was probably wrong; but made it clear that Captain could not continue to operate the #2 pump as it was officially deferred. Captain agreed to shut off #2 and keep #1 running in manual mode for duration of flight until the MEL discrepancy was corrected. I advised Captain I was filing a report as I believed the MEL to be incorrect based on what he was telling me; but nevertheless; he should not have turned on that #2 pump without exercising his emergency authority.