Online PHP editor | output for idLuh

<?php $json = <<<JSON [ { "id": 99961, "candidate": { "data": { "id": 125275, "firstName": "Jose", "lastName": "Zayas" } }, "dateAdded": 1667995574207 }, { "id": 99960, "candidate": { "data": { "id": 125274, "firstName": "CHRISTIAN", "lastName": "NEILS" } }, "dateAdded": 1667986477133 }, { "id": 99959, "candidate": { "data": { "id": 125273, "firstName": "Jose", "lastName": "Zayas" } }, "dateAdded": 1667985600420 }, { "id": 99958, "candidate": { "data": { "id": 125275, "firstName": "Jose", "lastName": "Zayas" } }, "dateAdded": 1667985600420 }, { "id": 99958, "candidate": { "data": { "id": 125275, "firstName": "Jose", "lastName": "Zayas" } }, "dateAdded": 1667985600420 } ] JSON; $array = json_decode($json, true); $duplicated = []; foreach ($array as $row) { $compositeKey = "{$row['candidate']['data']['firstName']} {$row['candidate']['data']['lastName']}"; $id = $row['candidate']['data']['id']; $grouped[$compositeKey][$id] = ''; if (count($grouped[$compositeKey]) > 1) { $duplicated[$compositeKey] = array_keys($grouped[$compositeKey]); } } var_export($duplicated);