There is not a way to prevent two Vendor IDs from having the same Vendor name.

Accounts Payable vendors are identified in the software by their Vendor IDs. This is the Primary Key record for the Vendor within the database. This ID (up to 10 characters) is unique per Vendor record. The Vendor name (up to 30 characters) can be the same or different from any other Vendor(s) as that field is not a Primary Key in the software.

The Vendor name displays during invoice entry for User verification.