So here's the offending key:

"mlg_addr_uniq_key" UNIQUE, btree (country, zipcode5, zipcode4, addres
+s1, address2)
[download]

The query you're using after the fact isn't checking against the key. You're looking at address1, city, and state... when address1 is the only field there that's part of the key. Try looking at just the fields that make up the key. I'd start by just looking for things that match or are like your address1, then paring down from that if necessary.