1)
What is the meaning of "Chamor Chamorasayim"?
1.
Rashi: [With the donkey's jaw I killed] big groups.
2.
Bereishis Rabah 98:13: It was born with a twin. Yefe To'ar - so it was very weak.
1
3.
Malbim: Chamarim (piles) fell from a nation that resembles a Chamor
2
(donkey).
1
Levush (YD 374:9): The nature of twins is to be weak.
2
See Radak, who explains that Chamor, Chomer and Chamorah are three different grammatical structures.