How is estate typically divided if both spouses die at the same time? 50/50 to secondary beneficiaries?

If both spouses have their own will that designates the other spouse as primary beneficiary, but they each have different secondary beneficiaries, and then the spouses die at the same time, will the estate be divided 50/50 and the secondary beneficiaries of each spouse divvying up the spouse's 50% share? By the way, I am in Illinois, if that matters.