[Avodah] Eating Two Kezeisim of Matza for Motzi-Matza.

[Micha Berger]

I figured this was the flipside of the shitah to only use two matzos,
not 3. Mima nafshach:

If you say that the concept of lechem oni is part of the usual YT
concept of se'udah, then
(1) the oni should mean that mishneh lekhem should be incomplete rather
than whole -- and not a third matzah; and
(2) one kezayis should be sufficient, since there is only one mitzvah.
It's like a regular Shabbos where we don't hold you need to take a
kezayis from each of the mishneh lechem.

However, if you say that they are distinct, then:
(1) mishneh lechem must be sheleimim, as usual, and the broken matzah
must be a third matzah; and
(2) one would need a kezayis from each -- the lechem mishneh and the
lechem oni.

Tir'u baTov!
-Micha

-- 
Micha Berger             The Maharal of Prague created a golem, and
micha at aishdas.org        this was a great wonder. But it is much more
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Fax: (270) 514-1507      "mensch"!     -Rabbi Israel Salanter