Except for being transposed down a perfect fourth and for one minor difference in the 3rd measure, it is exactly the "2. Canone" (2nd Canon) part of the Berthier cited (on p. 13, not p, 14). The only difference is on the first beat: The Bethier has Re Mi in the 3rd bar, where the round has Re-Sol Mi. Evidently this Magnificat round/canon is due to Berthier, with the minor emendation.Don't know for sure, but it reminds me of a Magnificat of Jacques Berthier, used a Pueri Cantores Congresses. It is on page 14 of this book.
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