Two signals with the same frequency in the same area can interfere? If one signal is transmitting form transmitter $TX_1$ with some frequency $X$ and some other transmitter $TX_2$ is sending some other signal with same frequency $X$ will there be any clash or interference between these two signals since these two transmitters $TX_1$ and $TX_2$ are located in the same area?
I would say yes almost certainly - it would depend on transmit power but if they are simultaneously broadcasting on the same frequency then there will be interference as they are in the same area. This is the reason valuable parts of the spectrum must be licensed by government agencies, to prevent multiple people using them at the same time without multiplexing etc.