Drop Down list dependent on 2 previous drop downs

I am trying to create a drop down list (without duplicates) that is based on 2 previous choices. Details of what is in workbook:

- Report tab is where everything is shown
- Dropdown tab is currently just a list of Product Names
- Spec Data tab is where all the data for the Report is pulled from

I have 2 named tables in the Name Manager for the drop downs for Spec Type and Test.

Spec_Type:
=OFFSET('Spec Data'!$A$1,MATCH(Report!$A3,'Spec Data'!$A:$A,0)-1,1,COUNTIF('Spec Data'!$A:$A,Report!$A3),1)

Test:
=OFFSET('Spec Data'!$B$1,MATCH(Report!$B3,'Spec Data'!$B:$B,0)-1,1,COUNTIF('Spec Data'!$B:$B,Report!$B3),1)

Problems I have:
- Both of these drop downs contain duplicates
- Test drop down is only based on Spec Type
- For instance Product=1, Spec Type=A, Test=Test4 does not exist, but Test4 does is exist for Product=1, Spec-Type=B