Answer:
OFAC has an excellent Q&A document on their website. In most cases you could simply explain that their name and information is similar and they'll need to contact OFAC. You could simply deny the customer the product or service and tell them they'll be notified in writing as to why in X number of business days, if you want to get them out of the branch. If you have a genuine fear, have Security called when the CSR goes to "check on" something.
First published on BankersOnline.com 1/31/05