Need a utility for deleting duplicate records from customer database

We are looking for a utility package (freeware or commercial) that would delete duplicate records from a customer database. (with standard fields like fname, lname, address, ph no. etc.). We need a package which has some kind of heuristics/logic built into it which takes into account different ways of writing the same address, spelling mistakes etc. I think that the direct marketing companies must be using some software to do this. We need the software for Informix OnLine 4.11 and Informix OnLine 5.01. If any one out there is using anything like this I'd appreciate the info. Thanks. -------- Yogen Sanghani yogen@IConNet.COM (212)972-4266