Duplicate records referenced across different databases
There are some great data cleansing products out there, one in particular that is actually top notch and affordable. I've come across DataMatch by Data Ladder, which is an excellent fuzzy matching and address standardization/address parsing tool used across business and would work really well for this situation. They offer a complimentary trial for new users.

In fact, an independent verified evaluation was done of the software comparing it to major software tools by IBM and SAS. There was a study done at Curtin University Centre for Data Linkage in Australia that simulated the matching of 4.4 Million records. It identified what providers had in terms of accuracy (Number of matches found vs available. Number of false matches)

1.  DataMatch Enterprise, Highest Accuracy (&gt;95%), Very Fast, Low Cost
2.  IBM Quality Stage , high accuracy (&gt;90%), Very Fast, High Cost (&gt;$100K)
3.  SAS Data Flux, Medium Accuracy (&gt;85%), Fast, High Cost (&gt;100K)