Date::Manip always parses dates in the local time zone (unless of course there is a zone attached to the date string), so you're right that my script wasn't exact. My apologies.

If you want to parse dates in UTC by default, use:

use Date::Manip::Date;
my $date = new Date::Manip::Date;
$date->config("setdate","now,UTC");
$date->parse('1988-12-13');
print $date->printf('%O -> %s');
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and that gives the same result as the DateTime script.