JSFiddle - React, Tailwind, and code Playground

JavaScript

function merge(array1, array2) {
    var ids = [];
    var merge_obj = [];
    array2.map(function(ele) {
        if (!(ids.indexOf(ele.id) > -1)) {
            ids.push(ele.id);
            merge_obj.push(ele);
        }
    });
    array1.map(function(ele) {
        if (!(ids.indexOf(ele.id) > -1)) {
            ids.push(ele.id);
            merge_obj.push(ele);
        }
    });

    console.log(merge_obj);
}

var array1 = [{
    "id": 1,
    "name": "Adam"
}, {
    "id": 2,
    "name": "Smith"
}, {
    "id": 3,
    "name": "Eve1",
     "name2": "Eve1"
}, {
    "id": 4,
    "name": "Gary"
}, ]

var array2 = [{
    "id": 1,
    "name": "Adam",
    "checked": true
}, {
    "id": 3,
    "name": "Eve",
    "checked": true
}, ];

merge(array1, array2);