Basic PHP clone isn't works correctly

[GreenMine]

use RIterator\Iterator;

$string = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla luctus fringilla iaculis.";
$separator = ' ';

$split_iterator = Iterator::split_str($string, $separator);
$clone_split_iterator = clone $split_iterator;

echo 'Fifth word of lorem ipsum is: ' . $clone_split_iterator->nth(4) . PHP_EOL;
echo 'Joined back str: ' . $split_iterator->join(' ') . PHP_EOL;

Result:

Fifth word of lorem ipsum is: amet,
Joined back str: Lorem adipiscing elit. Nulla luctus fringilla iaculis.

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