#basically the same:

%h_1 = (a,1,b,2);
%h_2 = (c,3,d,4);

%concat = (%h_1,%h_2);

print "k: $_\tv: $concat{$_}\n" for sort keys %concat;

__END__

k: a	v: 1
k: b	v: 2
k: c	v: 3
k: d	v: 4