I was just reading this wonderful article on the value of Late Latin texts for the reconstruction of linguistic history:
https://www.academia.edu/35770760/Late_Latin_the_evidence
He mentions various amusing examples of education affecting how people wrote in odd ways in early medieval Latin (which he includes within "Late Latin" in the article).
In particular, I liked the example of "et aliorum multorum filio bonorum". Filius boni is an expression equivalent to the later Old Spanish fidalgo < fīlius dē aliquod, meaning 'a good person', compare the late antique vir honestus. Apparently, the scribe thought of the expression as one word (and even wrote it as filiobonorum in fact), and since the citation form is filius boni, he figured the plural would end in -orum (since it's the plural of genitive -i) in spite of the phrase needing an accusative as it was after ante, and then,
tried to make the adjectives alios and multos agree with it. So, aliorum multorum agree with filiobonorum. Really a case of someone trying to follow grammar rules in an odd case and erring in an odd way.