Why does the Torah write "Machanayim", meaning two camps, when Yakov met only one group of angels?
Rashi: It refers to the angels of Chutz la'Aretz, who were returning to Heaven, and those of Eretz Yisrael, who were coming to accompany him. 1
Ramban #1: It is a matter of style not to differentiate between singular and plural with regard to place-names.
Ramban #2, Ohr ha'Chayim: It refers to Yakov's camp and that of the angels. 2
Moshav Zekenim: He saw two camps of angels, and thought that it is a Siman that he should divide into two camps. Really, it was a hint that the kingship of Yisrael would be divided into two in the days of Rechav'am, or that some Shevatim would inherit in Ever ha'Yarden.
Malbim: He saw that the angels are prepared for war, and understood that two camps will meet. This is why he sent messengers to Esav, for he knew that he is coming for war.
Why here, did the angels of Chutz la'Aretz arrive before those of Eretz Yisrael departed whereas at the beginning of the Parshah (in Yakov's dream), the angels of Eretz Yisrael departed before those of Chutz la'Aretz arrived?
Oznayim la'Torah:. The angels of Chutz la'Aretz could not depart before the angels of Eretz Yisrael arrived, so as not to leave Yakov unguarded, which was not the case at the beginning of the Parshah, 1 where the angels were not there to guard him, since Hashem was guarding him anyway. 2
How could Yakov be calm when seeing angels?
Tosfos ha'Shalem (2): His sons were not used to seeing angels in Lavan's house. They feared that the angels are Esav's men coming to fight. Yakov [who was used to seeing them in Yitzchak's house 1 ] assured them that they are angels; they are on our side.
Moshav Zekenim citing R. Yeshayah: He saw them in a dream. When he saw even one angel, he was astounded and said (verse 31) "I saw Elohim face to face, and I was saved!" 2
This is unlike Rashi (verse 4, from Bereishis Rabah, and Moshav Zekenim himself) who says that Yakov sent actual angels to Esav. We find that even Hagar saw angels, and was calm! Perhaps Yakov was astounded at seeing one angel because he tried to kill him, or because that angel was the Sar of Esav, i.e. the Satan. (PF)