my @x;
$x[6]= 1;
print "\$x[1] exists? ", ( exists $x[1] ? "yes" : "no" ), $/;
my @y= @x;
print "\$y[1] exists? ", ( exists $y[1] ? "yes" : "no" ), $/;
__END__
Produces:
$x[1] exists? no
$y[1] exists? yes