Why was he called Kushan Rish'asayim?
Sanhedrin 105a: He is Lavan, and Bil'am's father 1 . He did two Rish'os (evils) to Yisrael - in the days of Yakov, and [here] in the days of the Shoftim.
Radak #1: This was his name.
Radak #2: Perhaps Rish'asayim is the name of a place.
Radak citing Shochar Tov: His name alludes to two Rish'os (evils) that Aram did to Yisrael, one of Bil'am, and one of Kushan.
Chizkuni and Bartenura (both on Bamidbar 22:24) and Hadar Zekenim (Bereishis 31:52) say that he is Bil'am. Bil'am was killed in the days of Moshe (Bamidbar 31:8)! Ya'avetz (105a) says that the Gemara discusses Gilgulim. Ben Yehoyada (105a, citing the Ari Zal) - Lavan was the primary Neshamah; the others are offshoots.
