The Eglah Meshuleshet is against the Agalot that Yosef sent to Yisrael, to atone for the arbitrary death. And it is written there that "he slaughtered sacrifices to the G-d of his father Yitzchak (Bereshit 46:1)". He surely slaughtered Eglot. And for Yitzchak are the two kids of goats - Izim - that Yaakov gave him (Bereshit 27:9), to atone for the first two wars of Ez Meshuleshet. As for the third branch of Ez Meshuleshet, there will be outside atonement. G-d will show him the sacrifice (Bereshit 22:8), and the two went together (Bereshit 22:8), two Meshichim. VaYar v'Hineh Ayil (Bereshit 22:13), it is Ayil Meshulash.
This is the background of the story of Yoseph, the background of Yaakov's stealing of the Brachot, the background of Akeidat Yitzchak, and the background of it all, is Avraham's Brit Bein HaBetarim.
