My father died 9/26/07 and my mother died 10/17/07. I opened up an estate account
With bother of their names on the account. The IRS assigned me an EIN then recently
Assigned me another EIN for my mother's estate. Do I need to open up another estate
Account showing just my mother's name on it since all that my father had was left to
My mother?

Yes, being issued a separate EIN, requires a separate account

Yes, because you will need to show the estate moved over.

I have to ask about the estate account for your dad since if your mom was still alive, and if everything was owned jointly, there should have been no need for an esate account for him to start with
That is assuming things were all owned jointl.