I'd like to clarify what my concerns were, because I gather that they were unclear, although it looks as though Qianxi may have solved the mystery. It is common for ancient texts that were copied by hand to contain some errors (or even attempts at explanation inserted into the text). These may even accumulate over time. This occurred whether they were popular or obscure and regardless of religious tradition. The copyists were human after all. When they can, translators will often compare variations in different copies in order to produce the most accurate text possible.
For example, when Bhikkhu Bodhi translated the Saṃyutta Nikāya, he says he compared three different editions of the collection ("the Burmese-script Sixth Buddhist Council Edition," "the Sinhala-script Buddha Jayanti Edition," and the Pali Text Society "roman-script edition"). Each of these editions was itself the product of comparisons between different copies. He "also consulted footnotes on variants in the PTS edition." He did not regard any of these editions as absolutely perfect in all respects.
Or take a popular sutra that was translated into Chinese, The Buddhāvataṃsaka-mahāvaipulya Sūtra, commonly known as the Avataṃsaka Sūtra . The Indian monk Buddhabhadra translated it into Chinese in 420 C.E. The Khotanese monk Shikshananda translated it around 699 C.E. The Gandharan monk Prajñā translated it circa 798 C.E. Each "complete" translation was based on a copy with significant differences. The second translation, which is the most popular of the three, is "more than ten percent longer" than the first. The third translation, which is shorter than the first two, contains a 40th chapter, highly regarded by some, that is not found in the others.
Now it is surprising that "The Buddha Speaks the Dharani Sutra of Long Life and the Protection of Pure Youths" contains a common list of grievous misdeeds, but unlike all of the other sutras, omits "killing an arhat," replacing it with "killing an unborn child." In an instance like this, the most likely explanation would typically be that the Chinese text or the Sanskrit text from which it was translated (if there was one) is flawed, that an error was introduced into a copy at some point by an ancient copyist. This still seems like it may be a possibility. Perhaps this is truly an ancient sutra, but one that was discovered in the early 20th century. I don't know.
namo bhagavate śākyamunaye tathāgatāyārhate samyaksaṁbuddhāya | namaḥ sarvabuddhabodhisattvebhyaḥ ||
"Bodhisattva-mahāsattvas love all beings in the world equally, as if each were their only child..." Buddhāvataṃsakamahāvaipulya Sūtra