if there are conflicts on address, use the newest address. This should be an expansion of the merge rules from the rest of civi.
I just ran this with the new merge rule & $500+ now has 150 dupes - it was 389, but I also discovered that it was being too timid about running (waiting for incoming donations to only be 50 per minute) & so had not run for a while. I made it more aggressive
is a cases where the contacts have the same email but in one case it is on hold & in the other we have been emailing the person!