Maccabees in Hebrew Manuscripts?

As I'm working on Beckwith's views concerning the sequence of the Hagiographa (see here and follow the links back), I have come across a strange statement, which I find that I underlined once upon a time. In the context of discussing Origen's canon list (in Eusebius, Ecclesiastical History, 6.25.1-2), which includes a statement at the end about how Maccabees is outside of the books (ἔξω δὲ τούτων ἐστὶ τὰ Μακκαβαϊκά), Beckwith says the following:

[...] Origen is not including Maccabees among the 22 books, which one would not expect him to do, since there is no evidence that Maccabees was ever reckoned canonical by the Jews (though it sometimes appears as an appendix at the end of Hebrew biblical manuscripts, much as it does at the end of Origen's list) [...]

The statement I find strange is the one in parentheses. Surely Beckwith is not familiar with Hebrew biblical manuscripts that include Maccabees (any of them) as an appendix. Though 1Maccabees was originally written in Hebrew, nothing of this original Hebrew survives. Even Wikipedia knows that. Beckwith gives no endnote to substantiate his claim, which in itself is sort of odd, because he's pretty free with the endnotes in his book.

Is Beckwith perhaps thinking about Jerome's comment in his Preface to Samuel and Kings (the Prologus Galeatus), where he says Macchabeorum primum librum hebraicum repperi (p. 365, lines 55-56 in the Stuttgart Vulgate, ed. Weber and Gryson)? Jerome does not say where he has found 1Maccabees in Hebrew, but perhaps Beckwith surmised that it must have been at the end of a Hebrew biblical manuscript.

What else might he have been thinking?

UPDATE: I should have given the page number to Beckwith's book. It's p. 186.