In all kadeishim from RH to YK, we repeat the word l’eilah (l’eilah l’eilah). Some say l’eilah ul’eilah. (The former, “l’eilah l’eilah“, seems to the Rav to be more logical, but then again…who knows? But that is the Rav’s preference for those davening at the amud at the Shul).
- Aruch HaShulchan says to make sure to say “l’eilah l’eilah.”
- Mishneh Berureh when describing various nuances in Kaddish (in 56:2), just writes to say “l’eilah ul’eilah” between RH and YK, but doesn’t make any sort of issue of it. In 582:16, he just writes “we repeat the word l’eilah”
- Matteh Efrayim writes to say l’eilah l’eilah.