JSFiddle - React, Tailwind, and code Playground

JavaScript

var x = ['2530491','2530491','2530491','2530492'];
var mapOfValues = x.reduce(function(vals, current) {
    if (vals[current]) {
        vals[current]++;
    } else {
        vals[current] = 1;
    }

    return vals;
}, {});

for (var value in mapOfValues) {
    if (mapOfValues[value] > 1) {
        var idx = x.indexOf(value);
        x.splice(idx, 1);
    }
}

console.log(x);