strange behavior

gistfile1.pl

#!/usr/bin env perl
use strict;

local $, = " ";
my $registry = {1 => 1, 2 => 1, 3 => 1};

my $num      = [2,5];
say "first"  if @$registry{@$num};

my $num      = [5,2];
say "third" if @$registry{@$num};