$x = { foo => "abc", from => 'x' };
$y = { bar => "def", baz => "ghi", from => 'y' };

my $merged_x = { %$y, %$x };

my $merged_y = { %$x, %$y };

##</code><code>##

@{$x}{keys %$y} = values %$y; # Values in $y override values in $x