C:\>perl -MData::Dumper -MdaTA::duMPer -E "say Dumper(\%INC)"
$VAR1 = {
          'daTA/duMPer.pm' => 'C:/strawberry/perl/lib/daTA/duMPer.pm',
          'warnings/register.pm' => 'C:/strawberry/perl/lib/warnings/register.pm',
          'bytes.pm' => 'C:/strawberry/perl/lib/bytes.pm',
          'XSLoader.pm' => 'C:/strawberry/perl/lib/XSLoader.pm',
          'Carp.pm' => 'C:/strawberry/perl/lib/Carp.pm',
          'Exporter.pm' => 'C:/strawberry/perl/lib/Exporter.pm',
          'strict.pm' => 'C:/strawberry/perl/lib/strict.pm',
          'warnings.pm' => 'C:/strawberry/perl/lib/warnings.pm',
          'overload.pm' => 'C:/strawberry/perl/lib/overload.pm',
          'Data/Dumper.pm' => 'C:/strawberry/perl/lib/Data/Dumper.pm',
          'feature.pm' => 'C:/strawberry/perl/lib/feature.pm'
        };

C:\>

##</code><code>##

C:\>perl -MData::Dumper -MdaTA::duMPer -E "say for sort { lc($a) cmp lc($b) } keys %INC"
bytes.pm
Carp.pm
daTA/duMPer.pm
Data/Dumper.pm
Exporter.pm
feature.pm
overload.pm
strict.pm
warnings.pm
warnings/register.pm
XSLoader.pm

C:\>

##</code><code>##

C:\>perl -MData::Dumper -MdaTA::duMPer -E "my %oops; $oops{lc $_}++ for keys %INC; say for grep { $oops{$_}>1 } keys %oops"
data/dumper.pm

C:\>