use strict;
use warnings;
use YAML::Tiny;
my $yaml = YAML::Tiny->read('test.yaml');

##</code><code>##

---
rootproperty: blah
section:
  one: two
  three: four
  Foo: Bar
  one: again
  empty: ~

##</code><code>##

D:\>perl test.pl
YAML::Tiny found a duplicate key 'one' in line 'again' at test.pl line 5.