If the top screen has an small square box attached to the back with a door on it that as you open reveals a cf card in a slot, you already have the TseTse and have an a real "dual screen bb1". If you just have a monitor with nothing on the back, then you don't really have a "dual screen bb1" per se, you have a bb1 with 2 screens on it. The top screen is driven by something, either a tsetse board on real dual screen bb1's or the secondary video port on a bb2 mpu, in which case you would have what is known as a bb1.5.