When you turn on the "filters", the down-arrow shows you a list of "unique" entries. This list can be generated using a new temporary worksheet.
In a temp worksheet, copy a selected column of source data into column-A. Sort it. Copy cell A1 into B1. Select column-A. Select Data, Filter, Advanced Filter. In the pop-up, do the following:
select radio button for Copy to another location,
click inside of criteria range, then select cell B1
click inside of copy to, then select cell C1
select Unique records only
finally, click OK
This should result with all "unique" records appearing in column-C.
Hope this helps,