Here I send email to email address given in field.when I give different mail id in each field its working but If I send give same email address on every field the attachment is send one time instead of multiple time.Why?

 Private void SendEmailAttachment(Map<id,Mechanical_Service_Sheet__c> NewMSSMap,Map<id,Mechanical_Service_Sheet__c> oldMSSMap){
        //Variable Declaration
        List<id> listMSSIds=new List<Id>();    
        String templateName;
        List<String> mailId;
        System.Debug('--------Starting----------');
        
        // list of Mechanical Service Sheet Id
        for(Mechanical_Service_Sheet__c ms:NewMSSMap.values()){
            listMSSIds.add(ms.id);
        }
        
        List<Mechanical_Service_Sheet__c> MSSList=[SELECT id,Name,Copy_Email_for_Sheet__c,Email_Confirmation_to__c,Email_for_HQ_Notification__c,Engineer_s_Email_Address__c,RecordType.Name,Fire_Extinguisher_Service_complete__c
                                                   FROM Mechanical_Service_Sheet__c WHERE ID=:listMSSIds];
        for(Mechanical_Service_Sheet__c ms:MSSList){        
            if(Test.isrunningtest()||(ms.Email_Confirmation_to__c!=NULL && ms.RecordType.Name=='Sprinkler Service Sheet' &&  ms.Fire_Extinguisher_Service_complete__c==true &&
                   ms.Fire_Extinguisher_Service_complete__c!=oldMSSMap.get(ms.id).Fire_Extinguisher_Service_complete__c)){
                mailId = new List<String>();
                templateName='Sprinkler Confirmation';
                mailId.add(ms.Email_Confirmation_to__c);
                System.Debug('--------SSSmailId----------'+mailId);
                EmailAttachment(templateName,listMSSIds,ms,mailId,false);
            }
}
}
Private void EmailAttachment(String templateName,List<id> listMSSIds,Mechanical_Service_Sheet__c Mss,List<String> toAddress, Boolean isOriginal ){
        // get The Email Template Id 
        
        EmailTemplate template = [Select id,name,subject from EmailTemplate 
                                  where name =:templateName];
        
        //Added the below code to prevent the mail to owner
        Contact tempContact  = new Contact();
        tempContact.LastName ='TestLast';
        tempContact.firstName = 'Testname';
        tempContact.email = toAddress[0];
        tempContact.Account = [select id, name from Account limit 1];
        Insert tempContact;

        //get The List Of Attachments In Mechanical Service Sheet
        List<Attachment> attachmentList=new List<Attachment>();
        if(Mss.RecordType.Name=='Sprinkler Service Sheet' || Mss.RecordType.Name=='Riser Service Sheet'|| Mss.RecordType.Name=='Suppression System And Room Integrity Test'|| Mss.RecordType.Name=='Hydrant Service Sheet'|| Mss.RecordType.Name=='Fire Suppression Service Sheet'){
            attachmentList=[select name,body from Attachment Where ParentId IN:listMSSIds];
              }
        efaList = new List<Messaging.Emailfileattachment>();
        email = new Messaging.SingleEmailMessage();
        if(Mss.Email_for_HQ_Notification__c!=Null){
        String[] toAddresses=new String[]{Mss.Email_for_HQ_Notification__c};
        email.setToAddresses(toAddresses);
        
        }
        
        if(Mss.Copy_Email_for_Sheet__c!=Null){
        String[] toAddresses=new String[]{Mss.Copy_Email_for_Sheet__c};
        email.setToAddresses(toAddresses);
        
        }
       
        if(Mss.Engineer_s_Email_Address__c!=Null){
        String[] bccAddresses=new String[]{Mss.Engineer_s_Email_Address__c};
        email.setBccAddresses(bccAddresses);
        }
       
        email.setTemplateId(template.id);
        email.setTargetObjectId(tempContact.id);
        email.setWhatId(Mss.Id);
        email.setSaveAsActivity(false);
        System.Debug('--------attachmentList----------'+attachmentList);
        for(Attachment a:attachmentList){
            efa= new  Messaging.Emailfileattachment(); 
            efa.setFileName(a.name);
            efa.setBody(a.body);
            efaList.add(efa);
                                 
        }
        email.setFileAttachments(efaList);
        List<Messaging.SingleEmailMessage> lstMsgs = new List<Messaging.SingleEmailMessage>();
        lstMsgs.add(email);
        if(!Test.isRunningTest()){
        Messaging.sendEmail(lstMsgs);
        }
        
        //Delete the temp contact.
        delete tempContact;
        System.Debug('--------Ending----------'+lstMsgs); 
                                                                 
    }