Jeshurun is used only twice and both times by Moses. The first time is in Ha’Azinu. Vayishman Yeshurun Vayiva’at. Jeshurun became fat (complacent) and kicked over the traces. Or here in Vezot HaBeraha. There is no God like Jeshurun. Or there is no one before God to compare to Jeshurun. What or who is Jeshurun?
Once again, our commentators are divided. Some say it is a name of Moses. Others that is another name for Israel alongside Bet Yaakov or Israel or Benei Yisrael. Its root is Yashar meaning upright. So, it could be a way of saying an upright nation.
In which case why another name? It might have been that because of the rivalry of the tribes he preferred to use another, more inclusive name that would have applied to everyone there, in his final breath. But also, to seal this covenant with God and the people they had now become, in their own right, by accepting the covenant. Moses wanted to find a name that linked them to God rather than to the two names of Jacob.