use List::Util qw[ shuffle ];;

%h1 = map{ ("key$_", "value$_" ) } 0 .. 9;;
@selected = (shuffle keys %h1 )[ 0 .. 4 ];;
@h2{ @selected } = @h1{ @selected };;

printf "%-20s %-20s\n", $h1{ $_ }, $h2{ $_ } // '' for sort keys %h1;;
value0               value0
value1               value1
value2               value2
value3
value4               value4
value5
value6               value6
value7
value8
value9