It's not that voter fraud happens on both sides of the political spectrum, it's that the Democrat party is SO GOOD AT IT!!
Like the foreign online political contribution issue, if one party wants more money from uncertain/illegal sources then simply turn off the credit card verification software. In fact, send the foreign contributor emails requesting even greater amounts.
In the voter fraud case just have sympathetic election supervisors monitoring and counting votes. They'll overlook electioneering within the voting area, ignore people if they show up more than once, and, oh, by the way, make sure that some machines change the voters' choice prior to verifying their selection...if they don't catch the switch - too bad!