Duplicate check in multidimesional arrary in javascript expression

Q&A
1

I have a an attribute which is multiple in bdm 

now my requriement is i need to do validation for this multiple attributes such that values are not repeating so 

I have written javascript expression 

my approveObj looks like below :I should return a boolean value if duplicate founf in approvers 

[{"minMaxInfoId":0,"levelOfApprovers":1,"approvers":["Immediate Manager","DU Head"]},{"minMaxInfoId":0,"levelOfApprovers":2,"approvers":["DU Head","Procurement Committee"]}]

let result=false;
var approverObj= $data.formInput.approverLevelsInfoInput;
var app = approverObj.map(a => a.approvers);
var arr=JSON.stringify(app);
//console.log(JSON.stringify(app))

  let findDupesInMDArray = (arr) => {
  // flatten the array
  const flat = arr.flat();
  console.log(flat);
  // filter for dupes
 var isDuplicate= flat.filter((item, index) => flat.indexOf(item) != index);//here iam filtering for duplicates but how can i check for and return //a boolean values 
 console.log(isDuplicate);
 
}

// if(result) {
    //   return true;
   // } else {
    //  return false;
   //}
Please suggest . I have tried multiple codes but nothing works.