If the Torah will clarify that they gathered "Shnei ha'Omer la'Echad," why does it insert "Laketu Lechem Mishneh"?
Rashi: It means that its taste was special too.
Da'as Zekenim: We learn from "Shnei ha'Omer la'Echad" that the portion of Manna doubled on Shabbos, so that they ate two loaves of bread for each meal, instead of the usual one.
Shabbos 117b: To teach us the obligation to eat two loaves (at each meal) on Shabbos, or, as the Gemara concludes, to recite the Berachah over two loaves. 1
Shabbos, Ibid.: Since the Torah writes "Laketu Lechem Mishneh," rather than 'Achelu.' See Torah Temimah, note 30, who elaborates.
Why were people surprised when on Friday, they found that they had collected two Omers per person, seeing as Hashem had already informed them (in 16:5) that this would occur?
Rashi and Rashbam: Even though Hashem had informed Moshe about it, he had forgotten 1 to pass on the information to the people.
According to the Rashbam, he deliberately refrained from telling them about Shabbos, to let them discover its special properties for themselves.
Rashi (to Bereishis 2:3) writes that Hashem blessed the Shabbos through the Manna, in that a double portion fell on Yom Shishi. But even on a regular day, far more Manna fell than the Bnei Yisrael actually needed (Rashi to 16:21)! What then was the extra blessing for Shabbos?
Gur Aryeh (to Bereishis 2:3): The blessing was not how much fell, but rather than when they measured their Manna upon returning home, they found it to be double.
Rashi (to Bereishis 2:3) writes that Hashem blessed the Shabbos through the Manna, in that a double portion fell on Yom Shishi. But the extra portion was to eat on Shabbos, when no Manna would fall! What then was the extra blessing for Shabbos?
Da'as Zekenim: For each weekday meal, a half-Omer of Manna made one loaf, but the half-Omer that they baked for each of the three Shabbos meals made two loaves (Lechem Mishneh).
Gur Aryeh (to Bereishis 2:3): It is considered a blessing to receive a large quantity at once, rather than small amounts daily.
Maharal (Tif'eres Yisrael Ch. 40, p. 124): The blessing was that on Erev Shabbos, the Bnei Yisrael gathered the same amount as every other day, and then found it to be [miraculously] double. 1
It seems that according to Maharal, this miracle took place every Erev Shabbos that Bnei Yisrael were in the desert -- and not only the first week (when they were still unaware of this blessing). (For more about how the Manna expresses the blessings of Shabbos, and the sanctity of Shabbos, refer to Bereishis 2:3:1.3 and Bereishis 2:3:1.4 .)
QUESTIONS ON RASHI
Rashi writes: "They gathered double [the amount of] bread (Lechem Mishneh) - When they measured what they had gathered [upon returning to] their tents, they found it to be double." What is Rashi clarifying?
Gur Aryeh: Do not interpret that they went out to the field already with the intention of gathering a double amount. They knew [that during the week,] anyone who gathered more than an Omer of Manna would find that he had no more than anyone else (16:18).
