Maybe there is a duplication of information in other fields that may not even be appearing on the layouts you view when using this system.
The previous developer could have also used a different field for displaying names on contracts. For example, one that performed an initial lookup of separate first-name and last-name fields, then combined them into one field for the full name.
Either way, you will need to dig a little deeper into the database structure to make these discoveries. Begin by choosing File menu:Manage:Database and looking in the Tables and Fields tabs. Don't worry about ruining anything, just choose cancel to exit and no changes will be made.
Actually, it would be a good idea to make a copy of this database for experimentation purposes only. Just don't open them at the same time.
Yes, that and/or a key field that's referencing something in the same file which returns the first record it finds which is the original one you copied, or a related table with the original data you changed.
You need to look at the fields you think are displaying the wrong info and see where they get their data from and the fields you changed and how they store their data. The answer is there but this is the best I can do from here.