>I have a file that has multiple records that contain the same data in the field that I am trying to list in a comboBox but I only want to have those multiple records listed once. How do I do this without creating another file that lists the data once?

In addition to the other choices, you can keep a unique index tag on that field.

select MyData 
set order to MyUniqueField
scan
MyCOmbo.Additem(MyUniqueField)
endscan