If both P & VP candidates were from the same state, the Electors of that given state could not vote for both.
In a fxnal sense, in a close election, the VP candidate of the opposing party could be elected.
If you go back upthread, you will see that someone said that Cain couldn’t choose Newt because they were from the same state. They are both FROM GA, but Newt is a resident of VA (IIRC) not GA.