<?php

$a = array(
    (object) array("id" => 1),
    (object) array("id" => 3),
    (object) array("id" => 5),
    (object) array("id" => 6),
    (object) array("id" => 7)
);

$b = array(
    (object) array("id" => 1),
    (object) array("id" => 3),
    (object) array("id" => 5),
    (object) array("id" => 6),

);

$result = array_map(
    'unserialize',
    array_intersect(
        array_map(
            'serialize',
            $a
        ), 
        array_map(
            'serialize', 
            $b
        )
    )
);
          
print_r($result);

?>