Possibly - but I believe the algorithms and data the big casinos use may be out of the reach of smaller ones. Yes, as Colin said postcodes aren't expensive to check, but in themselves aren't foolproof either. The permutations of a letter missed in a postcode, surname, DOB etc. I reckon would need something quite complex, akin to those systems some use to spot collusion and bonus abuse.
But thats the thing, you can't miss a letter out of a postcode if you have to type it in and select your address from a drop down box. Then just have the system check the db for any self exclusions in the postcode and if there's a match, then manually check it. It wouldn't completely stop duplicate registrations, but would stop a high percentage.