Rav Henoch Leibowitz's Birkas Kohanim Duet
After he and one bochur were the only kohanim to duchen one Yom Tov, Rav Henoch Leibowitz greeted that talmid for years with a smile and the word 'duet.'
From the article
Another talmid told me that the rosh yeshiva would always say “duet” when he saw him. Why? One yom tov, this talmid and the rosh yeshiva were the only kohanim on the duchan. They chanted the melody together for Birkas Kohanim. Afterward, the rosh yeshiva approached the bachur and said, “Nu, we sounded pretty good together!”