We have problems with members trying to sign up multiple accounts to take advantage of referral rewards and free trial incentives. We require a mailing address and validate it against the USPS but have found this still doesn’t provide enough protection and it’s still too easy for a user to change an element on there address like “line 2” and have it still be valid.
What is the best away to detect if a different user has already signed up with an address?
Example of address variations:
59 Grant Ave
Floor 2
59 Grant Ave
Suite 2
The problem with anything resembling exact comparisons is that the a street address may have multiple tenants in different apartments / offices etc.
We are using Rails 3, MySQL, Memcache, Sphinx
We face a similar problem, although in a different context. There’s not that much you can do, we basically wrote a method that tries to identify possible duplicates based on normalized phone number, normalized street address, Leveshtein distance of name and address, physical distance when geo-coding the address etc. Finding out if something really is a duplicate still needs a human, but at least you can reduce the number of possible candidates significantly.