You probably want a record of votes with times and not just a simple counter.
And I'm unsure how adding timestamp helps with the problem you're trying to solve, don't you just need Sum(machine vote count at location X) == voters visiting location X. (Also this hueristic is kinda leaky since how do you account for voters protesting with intentional spoilers?)
Defence in depth.
A very least now they have to bring a math nerd into the conversation, increasing the footprint of the operation.