Simple cross-check.
Compare Florida and New York names.
Now, there is a short list of duplicates.
Now, toss in the union membership list...
IIRC, that was done a few years ago. Many duplications were found. There were several threads here at FR on it at the time.
And then check for Absentee ballot requests, esp those mailed to Florida. Lots of New Yokers vote in both states. Mostly Democrats. This is good news.
Currently there is a trial ongoing in Broward County and other investigators. Stay turned...
Also need to reference out of state college students in NY with the names of those in other towns. Colleges routinely advise students to register to vote locally in order to contaminate the local government.
Good thing Florida has a republican administration or I might have thought NY had already cross-checked with Florida and removed the duplicate names (but not permanently).