The previously selected closed task is cloned with below code;
AuthenticateWithNoHelp AWNH = new AuthenticateWithNoHelp();
             
 
             OrganizationServiceProxy CurrentOrganizationServiceProxy = AWNH.ActiveOrganizationServiceProxy();
             
             if (CurrentOrganizationServiceProxy != null)
             {
                 
                 ActiveService CurrentService = new ActiveService(CurrentOrganizationServiceProxy)
                  
                 List<Task> ListTask = (from c in CurrentService.TaskSet
                                        where c.StateCode.Equals(TaskState.Completed)
                                          && c.ActivityId.Equals(new Guid("0602713D-FE39-E211-AE0A-005056B60039"))
                                        select c
                                         ).ToList<Task>();
 
                 Guid cloneId = Guid.Empty;
                 Entity clone = EntityExtensions.Clone(ListTask.FirstOrDefault(), false);
                 clone.Id = Guid.NewGuid();
                  
                 SetStateRequest CurrentEntityStatus = new SetStateRequest();
                 CurrentEntityStatus.State = new OptionSetValue(((OptionSetValue)clone.Attributes["statecode"]).Value);
                 CurrentEntityStatus.Status = new OptionSetValue(((OptionSetValue)clone.Attributes["statuscode"]).Value);
 
                 clone.Attributes.Remove("statuscode");
 
                 clone.EntityState = null;
                 
                 cloneId = CurrentOrganizationServiceProxy.Create(clone);
 
                 CurrentEntityStatus.EntityMoniker = new EntityReference(clone.LogicalName, cloneId);
                 CurrentOrganizationServiceProxy.Execute(CurrentEntityStatus);
        }