If you're only duplicating one value, you can use

my %h = (
    HELP => $_ = sub {print "help\n"},
    "?"  => $_,
    SAVE => sub {print "save\n"},
);
[download]

You have to use one variable per value though:

my ($help, $save);
my %h = (
    HELP => $help = sub {print "help\n"},
    "?"  => $help,
    SAVE => $save = sub {print "save\n"},
    EXIT => $save,
);
[download]