If they had seperate phone lines for each person and only two people were left, wouldn't this always result in a near tie every time.
I.e. if the phone lines are saturated with calls, both lines would be receiving calls at the highest rate possible. So, it should always be a tie, plus or minus a small error.
Exactly. That is what happened last year in the Aiken/Studdard showdown. The phone system reached capacity and minor differences in the recording time of the canned response allowed Ruben's number to accept slightly more calls.