Used the component "ibo5.7.13.2411" and migrate to the latest version "ibo5.9.1.b2522" property of the query Unidirectional stopped working.
Now to to set the property "Unidirectional = true" data repeat.
The following example...

procedure TForm1.Button1Click(Sender: TObject);
begin
 qCustomer.Active := false;
 qCustomer.SQL.Text := 'select * from citys';
 qCustomer.Unidirectional := True;
 qCustomer.Active := true;
 qCustomer.first;
 while not qCustomer.eof do
 begin
   ListBox1.Items.Add(qCustomer.FieldByName('name_city').AsString);
   qCustomer.next;
 end;

end;


If the property is "Unidirectional = true" values are:

Alabama
Alaska
Arizona
Arkansas
California

If the property is "Unidirectional = false" values are:

Alabama
Alabama
Alabama
Alabama
Alabama

Att
Jonathan Fabricio Seibel