Mozart's Requiem

I'm still making my way through The Argo Years, the 28-disc box set of Neville Marriner and the Academy of St. Martin-in-the-Fields.  To-night, it was Mozart's Requiem.  I hadn't heard this particular recording before, but I do have it performed by Orchestra e Coro della RAI.

The first few notes of the Benedictus sounded familiar, and it didn't take me too long to discover that I'd heard them in the second movement of Mendelssohn's Organ Sonata in A major, Op. 65, No. 3.  (I just listened to Peter Hurford's recording a couple days ago.)

I wasn't sure how similar they were, so I looked up the music for both of them:

(notation found here and here)

The note values and time signatures are different, and the melodies don't really resemble each other after the fifth note, but the notes do occur in the same intervals (even if they're in different keys).

However, I'm not sure if this was intentional on Mendelssohn's part.