I'm a little bemused by your sample data. The dates against each customer entry on the right hand side are always the same.

If that's always the case, then use the VLOOKUP that the other guys have suggested. That will always return the first date that it finds for the customer.

If there may be different orders/dates, you might want to use the formula that I have provided. It will return blanks if you have more entries onthe left hand side than the right hand side.

Regards, TMS