Online PHP editor | output for FVfM4

<?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 } ] JSON; $array = json_decode($json, true); $grouped = []; foreach ($array as $row) { $compositeKey = "{$row['candidate']['data']['firstName']} {$row['candidate']['data']['lastName']}"; $grouped[$compositeKey][$row['candidate']['data']['id']] = $row['candidate']['data']['id']; } $result = []; foreach ($grouped as $id => $group) { if (count($group) > 1) { $result[$id] = array_values($group); } } var_export($result);