TEMS mobile is always showing the serving BCCH RxLev in the neighbour list (as far as i remember).
therefore you can see the “reported” rxlev of the TCH + the BCCH rxlev at the same time.
it shows how much PC attenuation is made, but it can also show that the TRX on which is the TCH is having a very poor TX POWER compared to the BCCH power. That’s the case when you have TRX swapped between different sectors 🙂 (or also, TRX failure)
(or concentric cells, as mania said)