I thought we had to also.  How do you "true up" the number of voters?  We count our voters and if the two lists don't match up, we go page by page to see where the discrepancy is.  The number of voters has to match the number of ballots. What happens if the entrance checker puts a mark in the wrong place and that voter shows up and he's already marked off? The exit check list shows him not checked off. (The thinking here being that the odds of both checkers getting it wrong are slim.)
I wonder what the official answer is here?
Marianne in Windsor
Justice of the Peace