remove duplicate from list of object

public static List<State__c> getState(){
        List <State__c> first = [SELECT Id,Name,Child__r.Name FROM State__c];
        List<State__c> uniqueValue = new List<State__c>();
        Set<State__c> myset = new Set<State__c>();
        for (State__cs : first) {
            if (myset.add(s)) {
                uniqueValue.add(s);
            }
        }
        return uniqueValue; 
    }

suucces[{"Id":"a0b5E000002VSuXQAW","Name":"Abbes","Child__c":"a0Z5E000002s12BUAQ","Child__c":{"Name":"Abbes","Id":"a0Z5E000002s12BUAQ"},"Public__c":true},{"Id":"a0b5E000002VSajQAG","Name":"Abbes","Child__c":"a0Z5E000002s12BUAQ","Child__r":{"Name":"Abbes","Id":"a0Z5E000002s12BUAQ"},"Public__c":true}]