That is exactly how FileMaker is designed to work. When you specify that a value list draw it's values from a field, Filemaker actually uses the field's index (which should never include duplicate values) to produce the value list. But think about this for a minute, if you could display such duplicate values how would the user know to select the second such duplicated value instead of the first or vice versa?
I recommend you restructure your table so that each product has a unqiue Serial number and base your relationships on this unique serial number--not the duplicate filled product name field.
Next, use a text field with an auto-entered calculation that combines the product name with the other make, style fields so that this entry will be unique. Set a field validation rule on it to enforce unique values only to make sure you don't have any duplicates here. Using this field in a value list will allow the user to distinguish between items with duplicate names in order to know which product is the one they want.
Thanks Phil...works well.