Well, you can't just copy my code into your program before thinking about or trying it on its own. If you copy the code I give you now into a small testing program as it is it will work. You need to modify to your needs so.
Private Sub Form_Load()
Dim str As String
Dim ar(5) As String
ar(0) = "apple"
ar(1) = "banana"
ar(2) = "plum"
ar(3) = "apple"
ar(4) = "plum"
Debug.Print (Combo1.ListCount)
For i = 0 To 4
str = ar(i)
For j = 0 To Combo1.ListCount - 1
If str = CStr(Combo1.List(j)) Then
MsgBox ("Double Entries not allowed")
Exit For
End If
Next
If str <> CStr(Combo1.List(j)) Then
Combo1.AddItem str
End If
Next
End Sub