Looking For Duplicates

I have 9500 contacts and some are duplicates. However the records are not complete duplicates of eachother. Some may be duplicates but all the fields in each record are not the same. For example I might have a john smith with an address and email address and other information and there may be a duplicate of him as john smith with all the same information as well as a date of birth. I would want to keep the record that has his date of birth because it contains more information and is therefore a more valuable record and thus the one to keep. The problem comes when I need to find which duplicate I want to keep. Is there some sort of script or module that can identify duplicate records or records that appear to be duplicate? Has anyone run into this issue before. What is the most efficient way to clean these records to identify duplicates and keep the one that has the most information on the contact.

Thanks!

Erik