appearing on filter name

  appearing on filter name

Hi -
I have a Customer form that collects First_Name and Last_Name of customers.  I have a separate form for Orders, that uses a look-up field from the Customer form that combines First_Name and Last_Name, called Customer_Name.  On the Order report, I have a filter for Customer_Name.  The Customer_Name appears just fine on the filter, but once I select it, the Customer_Name appears as "LastName, FirstName" --- any idea why it would be adding the   in there?  It should read Last_Name, First_Name, as it does from the drop down filter choice.
Thanks.