1const values = [
2  { name: 'someName1' },
3  { name: 'someName2' },
4  { name: 'someName3' },
5  { name: 'someName1' }
6]
7
8const uniqueValues = new Set(values.map(v => v.name));
9
10if (uniqueValues.size < values.length) {
11  console.log('uniqueValues')
12}

1var yourArray = [
2
3{Index: 1, Name: "Farley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"},
4{Index: 2, Name: "Farley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"},
5{Index: 3, Name: "Tarley, Charley", EmployeeCode: "12", PaymentType: "Void", CheckDate: "01/04/2012"}
6];
7
8   unique = [...new Set(yourArray.map(propYoureChecking => propYoureChecking.Name))];
9if (unique.length === 1) {
10console.log(unique);
11}