There are 4 chips on total in the Athlon II 64* lineup on socket AM2, here are the CPU World links:
Athlon II x4 645 (rev. E0) -> Zosma
Athlon II x4 645 -> Propus
Athlon II x4 640 (rev. E0) -> Zosma
Athlon II x4 640 -> Propus
Only the Zosma chips are unlockable and they are also the ones which misreport as Thuban in CPU-Z. The "T" at end of the name seems to be a CPU-Z invention for the Zosma cores, I haven't seen a reference to it anywhere else except on HWBot, which probably got it from CPU-Z ?. I don't have any of these chips in hand at the moment but will send you a validation once I do, tbh I doubt CPU-Z developers have fixed this.
Edit: The much more popular 960T BE also has the same issue. I'll validate it on 1.86 in a couple of hours and add the screenshot here.