I'm trying to get duplicate contacts using batch apex, for that I want to check a field lender__c on contact if(lander__c == 'loanDepot') then I want to check their email and accounts if both are same then I want to mark the as duplicate

for the my code is as follows

global class DuplicateContactsBatch implements Database.Batchable<sObject>, Database.Stateful{

global Database.QueryLocator start(Database.BatchableContext BC){
    return Database.getQueryLocator('Select id, Name, AccountId, Lender__c, ownerId, Email from contact order by CreatedDate desc limit 10'
    );
}

global void execute(Database.BatchableContext bc, List<Contact> scope){
    List<Contact> contactslist = new List<Contact>();
    
    
    map<String,List<Contact>> Contactmap = new map<String,List<Contact>>();
    
    for(Contact objcon : scope)
    {
        if(objcon.Lender__c == 'loanDepot' )
        {
            if(Contactmap.containsKey(objcon.email+objcon.AccountId))
            {
                Contactmap.get(objcon.email+objcon.AccountId).add(objcon);
                System.debug('Get Contactmap>>'+Contactmap);
            }
            else
            {
                List<Contact> listcon = new List<Contact>();
                listcon.add(objcon);
                Contactmap.put(objcon.email+objcon.AccountId,listcon);
            }
            System.debug('Contactmap-->'+Contactmap);
        }   
    }
    
 }
global void finish(Database.BatchableContext bc){
}   

}

Here I'm able to add all the duplicate contacts in the map. If suppose their are 3 contacts whose email and account id is same I want to mark 2 contacts as duplicate which are recent one and one as original, how can I do this.? and for this is it ok to use batch apex?

I'm trying to get duplicate contacts using batch apex, for that, I want to check a field lender__c on contact if(lander__c == 'loanDepot') then I want to check their email and accounts if both are same then I want to mark the as duplicate

for my code is as follows

global class DuplicateContactsBatch implements Database.Batchable<sObject>, Database.Stateful{

    global Database.QueryLocator start(Database.BatchableContext BC){
        return Database.getQueryLocator('Select id, Name, AccountId, Lender__c, ownerId, Email from contact order by CreatedDate desc limit 10'
        );
    }
    
    global void execute(Database.BatchableContext bc, List<Contact> scope){
        List<Contact> contactslist = new List<Contact>();
        
        
        map<String,List<Contact>> Contactmap = new map<String,List<Contact>>();
        
        for(Contact objcon : scope)
        {
            if(objcon.Lender__c == 'loanDepot' )
            {
                if(Contactmap.containsKey(objcon.email+objcon.AccountId))
                {
                    Contactmap.get(objcon.email+objcon.AccountId).add(objcon);
                    System.debug('Get Contactmap>>'+Contactmap);
                }
                else
                {
                    List<Contact> listcon = new List<Contact>();
                    listcon.add(objcon);
                    Contactmap.put(objcon.email+objcon.AccountId,listcon);
                }
                System.debug('Contactmap-->'+Contactmap);
            }   
        }
    }
    global void finish(Database.BatchableContext bc){
    }   
}

Here I'm able to add all the duplicate contacts in the map. If suppose their are 3 contacts whose email and account id is same I want to mark 2 contacts as duplicate which are recent one and one as original, how can I do this.? and for this is it ok to use batch apex?