Question

[Fryy]

When a civilian cargo is transmitting on VHF 120.75(TWR) and another plane, a military type is transmitting on UHF 254.4(also TWR) does the tower controller have two seperate comms, or do both planes hear the controller speak, but not eachother? I hope that made sence.

[davolijj]

In most cases controllers are transmiting on VHF and UHF frequencies simultaneously.  As LiveATC and scanner spectators we usually only hear the VHF side of the exchange (unless you have UHF freqs available).  And yes, the aircraft in your scenario will only hear the controller transmitting, not eachother.