Selecting RF port on LimeSDR

Thank.
by set the device argument with (driver=lime,soapy=0,serial=000etcabcef,nchan=2) osmocom-sdr work correctly but when see spectrum channel RX-2 it has -10db smaller than spectrum channel (fft sink) in RX-1. i think that two channel (RX-1 H) and (RX-2 H) are same but when see deference between them i really don’t know about this. please help me again. thank a lot.
Best Regard.