Derech
I didn’t say the shiur was a k’beiah. i said it was a k’zayis.
It is a hiddur to have before you at least one kneidel the size of a beiah because of Chashivus, but this is, of course, not the shiur.
see the Rachnachel, sif kuf zion bais, simmon gimmel.
As far as I know the reason for 2 kneidlach is not because of a concern for the shiur, but rather as a remez to the two omers of mann that were given on Shabbos (Yom Tov also?). At least that’s how I recall it.