c# .net parallel foreach Violation of PRIMARY KEY constraint

Hi ,
I am using below code ,
 Task[] taskArray = new Task[3];            for (int i = 0; i < taskArray.Length; i++)            {                taskArray[i] = Task.Factory.StartNew((Object obj) =>                {                    PNRMonitorJob pnrMonitorJob = obj as PNRMonitorJob;                    if (pnrMonitorJob == null)                        return;     &nbs ...