Prevent Duplicate Entries when Editing Data using Userform

Private Sub txtTag_Change()  'Add DBN Prefix
    Static abort As Boolean
    If abort Then abort = False: Exit Sub
    With txtTag
          If Not .Text Like "DBN*" And .Text <> vbNullString Then
            abort = True
            .Text = "DBN" & .Text
        End If
    End With
    
    If Not IsError(Application.Match(txtTag.Text, Columns(10), 0)) Then
        MsgBox "Duplicate Entry", vbOKOnly
        txtTag = vbNullString
    End If
End Sub