Mehdi,
Signals present when the input is terminated are “residual responses” or sometimes “residual spurious”.
The specification for the BB60D is -120 dBm. This is one of the strengths of the BB60D.
The specification for the SP145 is -103 dBm, similar to the BB60C.
This is not directly related to the preselector, and is more closely related to filtering and isolation differences in the architectures.