Error 1 The call is ambiguous between the following methods or properties: 'UnBlendedCS1_Oct1.DriveTime.GeoprocessorTask_ExecuteCompleted(object, ESRI.ArcGIS.Client.Tasks.GPExecuteCompleteEventArgs)' and 'UnBlendedCS1_Oct1.DriveTime.GeoprocessorTask_ExecuteCompleted(object, ESRI.ArcGIS.Client.Tasks.GPExecuteCompleteEventArgs)'
Thanks for your review and provide your hint for the solution.
Ambiguous call means you have defined that method more than once so it is unsure which method to call. Find all references on GeoprocessorTask_ExecuteCompleted, to see if it was duplicated.