The account number is essential for proper posting of payments to the correct account. For multiple accounts with the same vendors, it will be necessary to have separate vendor records for each account.
Managing multiple vendor records for the same vendor
To keep this manageable, an easily identifiable naming convention is recommended, such as using the vendor name with the last 4 digits of the account for easy identification.
There are 2 accounts with AT&T for the same remit to address, account # 123456789 & 987654321. Create 2 vendors and name them: AT&T 6789 and AT&T 4321. The Pay to field should be AT&T but the vendor names will be unique and easily identifiable.