Exit polling has proven to be the best way to accomplish what you are after with this suggestion of mirror voting. It would have no chance of working because in the end you would be asking people to vote twice.
I think the answer is to intimidate those who actively and frequently commit voter fraud by voting in multiple places...
Signs should be made visible at polling places which read “You only have a right to vote ONCE!” and/or “Video surveillance in progress!!!”. Any time a bus rolls into a polling area, the first thing riders should see is at least 20 different people taking video recordings with phones etc.
Make these cheaters think twice.
1. ID would be required.
2. Exit polling would be imperative.
3. This would catch them by surprise, no time to mobilize.
4. Rick reward. The reward is high with low risk.
5. Motivate people to get active.
6. Give us hard pre-election evidence.
7. We have amazing computer savvy people that could create the secure voting necessary, to get the raw data we would need.
8. You can’t prove anything without data after the election.
9. Would show our absolute resolve.
10. Better than doing nothing.