$markIn = $dateFormat->parse($markIn_value,  $locale, true);
$diff = $markIn->fieldDifference($markOut, AgaviDateDefinitions::MILLISECOND);
 12345 == (int)$markIn->getTime() // modified by fieldDifference




$markIn = $dateFormat->parse($markIn_value,  $locale, true);
$markInClone = clone $markIn;
$diff = $markInClone->fieldDifference($markOut, AgaviDateDefinitions::MILLISECOND);
 67890 == (int)$markIn->getTime() // as expected