Hi, 

  Below trigger is working perfect in after update but this is not working after creating the records this is giving error below . Please suggest me what might be the issue with the code 

Error: Invalid Data. 
Review all error messages below to correct your data.
Apex trigger quotesync.QuoteLineSyncTrigger caused an unexpected exception, contact your administrator: quotesync.QuoteLineSyncTrigger: execution of AfterInsert caused by: System.DmlException: Update failed. First exception on row 0 with id 0QL180000008e3zGAA; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, autosync: execution of AfterUpdate caused by: System.ListException: Duplicate id in list: 0Q0180000008iPYCAY (): []: (quotesync)​
 

trigger autosync on QuoteLineItem (after insert, after update) 
{
 Decimal LineMaxDiscount;
 Decimal LineMaxACV;
 Map<ID, Quote> ParentQuote = new Map<ID, Quote>();
 Integer L1Count;
 Integer L2Count;
 Integer L3Count;
 Integer L4Count;
 String SALREPID;
 String MRGID;
 String SALID;
 String CFOID;
 String Level;
   
 List<Id> listIds = new List<Id>();
 //Set<Id> listIds = new Set<Id>(); 
    
 List<Quote> QuotetList = new List<Quote>();  
 
 for (QuoteLineItem childquoteline : Trigger.new) {
        listIds.add(childquoteline.QuoteId);
    }
    
  ParentQuote = new Map<Id, Quote>([SELECT id,Level_1__c,Level_2__c,Level_3__c,Level_4__c FROM Quote WHERE ID IN :listIds]);
  
  List<AggregateResult> GetLineDiscount = [select max(Discount_Percent__c) QuoteLineMaxDiscount,SUM(UnitPrice) QuoteLineMaxACV from  QuoteLineItem where quoteid in :listIds];
     
  for (AggregateResult QuoteMaxDiscount : GetLineDiscount)
  {
  LineMaxDiscount = (Decimal)QuoteMaxDiscount.get('QuoteLineMaxDiscount');
  LineMaxACV = (Decimal)QuoteMaxDiscount.get('QuoteLineMaxACV');
  }
      
  Quote Qot = [select id,OpportunityID
               from quote
               where
               id in :listIds];    
      
  Opportunity Opp = [select Subscription_Term__c,ownerid
                    from opportunity
                    where
                    id = :Qot.OpportunityId];
                         
  User Usr = [select managerid from user where id = :opp.ownerid]; 
                       
   if ( Opp.Subscription_Term__c != null &&
        LineMaxACV != null &&
        LineMaxDiscount != null)
   {                       
         
     List<AggregateResult> Level1 = [select count(id) Level1Count
                                      from Discount_Schedule_Matrix__c
                                      where
                                      Subscription_Term__c = :Opp.Subscription_Term__c and
                                      ACV_Lower__c <= :LineMaxACV  and ACV_Upper__c >= :LineMaxACV and
                                      Sales_Rep_Lower__c <= :LineMaxDiscount and Sales_Rep_Upper__c >= :LineMaxDiscount];
                                      
     List<AggregateResult> Level2 = [select count(id) Level2Count
                                         from Discount_Schedule_Matrix__c
                                         where
                                         Subscription_Term__c = :Opp.Subscription_Term__c and
                                         ACV_Lower__c <= :LineMaxACV and ACV_Upper__c >= :LineMaxACV and
                                         Direct_Manager_Lower__c <= :LineMaxDiscount  and Direct_Manager_Upper__c >= :LineMaxDiscount];
     
     List<AggregateResult> Level3 = [select count(id) Level3Count
                                        from Discount_Schedule_Matrix__c
                                        where
                                        Subscription_Term__c = :Opp.Subscription_Term__c and
                                        ACV_Lower__c <= :LineMaxACV and ACV_Upper__c >= :LineMaxACV and
                                        SVP_Lower__c <= :LineMaxDiscount  and SVP_Upper__c >= :LineMaxDiscount];

    List<AggregateResult> Level4 = [select count(id) Level4Count
                                        from Discount_Schedule_Matrix__c
                                        where
                                        Subscription_Term__c = :Opp.Subscription_Term__c and
                                        ACV_Lower__c <= :LineMaxACV  and ACV_Upper__c >= :LineMaxACV  and
                                        CEO_CFO__c <= :LineMaxDiscount and CEO_CFO_Upper__c >= :LineMaxDiscount ];

                                    
     for (AggregateResult arLevel1 : Level1)
     {
      L1Count = (Integer)arLevel1.get('Level1Count');
     System.Debug('Level 1:' + L1Count);
     }
     
     for (AggregateResult arLevel2 : Level2)
     {
     L2Count = (Integer)arLevel2.get('Level2Count');
    System.Debug('Level 2:' + L2Count);
     }
   for (AggregateResult arLevel3 : Level3)
   {
   L3Count = (Integer)arLevel3.get('Level3Count');
   System.Debug('Level 3:' + L3Count);
   }
   for (AggregateResult arLevel4 : Level4)
   {
   L4Count = (Integer)arLevel4.get('Level4Count');
   System.Debug('Level 4:' +L4Count);
   }

   If( L1Count != 0 )
   {
    SALREPID = Opp.OwnerId;
    MRGID = null;
    SALID = null;
    CFOID = null;
    Level = '1';
   }
   else If ( L2Count != 0 )
   {
    SALREPID = NULL;
    MRGID = Usr.managerid;
    SALID = null;
    CFOID = null;
    Level = '2';
   }
   else If ( L3Count != 0 )
   {
    SALREPID = NULL;
    MRGID = Usr.managerid;
    SALID = '00580000007jaoA';
    CFOID = null;
    Level = '3';
   }

   else If ( L4Count != 0 )
   {
    SALREPID = NULL;
    MRGID = Usr.managerid;
    SALID = '00580000007jaoA';
    CFOID = '00580000006HV0w';
    Level = '4';
   }
              
 for (QuoteLineItem gqtl :trigger.new)
 {     
   Quote MyParentQuote = ParentQuote.get(gqtl.QuoteId);
                  
    MyParentQuote.Test_Sudhir__c = String.valueOf(LineMaxDiscount);
    MyParentQuote.Test_Sudhir_ACV__c = String.valueOf(LineMaxACV);
    MyParentQuote.Level_1__c = SALREPID;
    MyParentQuote.Level_2__c=MRGID;
    MyParentQuote.Level_3__c=SALID;
    MyParentQuote.Level_4__c=CFOID;
    MyParentQuote.Test_Sudhir_Level__c=Level;
    
    QuotetList.add(MyParentQuote);
    
     
  }  
  
  update QuotetList;
  
  
  }
 
}

Thanks
Sudhir