I've seen examples of half USA/ half UK fake addresses more and more both here and on Feepay- and I'm sure they all trace back to Nigeria!
I think there is some random address generator software out there that the Nigerian scammers are using- it probably fools automated address checkers on the big sites (Amazon/Ebay etc..) for both UK and USA. It only gets spotted when a 'human' checks it!
My advice to anyone who gets a bidder with one of these crazy Miami/Essex type hybrid addresses is report them to EBID straight away- plus post their user IDs here so sellers can blackball them pending their suspention